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SYSTEMATIC  BOTANY 


CAMPBELL 


GINN    COMPANY 


EDUCATION  DEPT, 


O 


ELEMENTS 


STRUCTURAL  AND  SYSTEMATIC  BOTANY, 


HIGH   SCHOOLS   AND   ELEMENTARY 
COLLEGE   COURSES. 


BY 

DOUGLAS  HOUGHTON  CAMPBELL,  PH.D., 

PROFESSOR  OF  BOTANY  IN  THE  INDIANA  UNIVERSITY. 


BOSTON,  U.S.A.: 

PUBLISHED   BY    GINN   &   COMPANY. 
1890. 


COPYRIGHT,   1890, 

BY  DOUGLAS  HOUGHTON  CAMPBELL 


ALL  RIGHTS  RESERVED. 

EDUCATION  DEPTt 


TYPOGRAPHY  BY  J.  S.  GUSHING  £  Co.,  BOSTON,  U.S.A 


PRESSWORK  BY  GINN  &  Co.,  BOSTON,  U.S.A. 


PREFACE. 


THE  rapid  advances  made  in  the  science  of  botany  within 
the  last  few  years  necessitate  changes  in  the  text  books  in 
use  as  well  as  in  methods  of  teaching.  Having,  in  his  own 
experience  as  a  teacher,  felt  the  need  of  a  book  different  from 
any  now  in  use,  the  author  has  prepared  the  present  volume 
with  a  hope  that  it  may  serve  the  purpose  for  which  it  is 
intended ;  viz.,  an  introduction  to  the  study  of  botany  for  use 
in  high  schools  especially,  but  sufficiently  comprehensive  to 
serve  also  as  a  beginning  book  in  most  colleges. 

It  does  not  pretend  to  be  a  complete  treatise  of  the  whole 
science,  and  this,  it  is  hoped,  will  be  sufficient  apology  for  the 
absence  from  its  pages  of  many  important  subjects,  especially 
physiological  topics.  It  was  found  impracticable  to  compress 
within  the  limits  of  a  book  of  moderate  size  anything  like  a 
thorough  discussion  of  even  the  most  important  topics  of  all 
the  departments  of  botany.  As  a  thorough  understanding  of 
the  structure  of  any  organism  forms  the  basis  of  all  further 
intelligent  study  of  the  same,  it  has  seemed  to  the  author 
proper  to  emphasize  this  feature  in  the  present  work,  which 
is  professedly  an  introduction,  only,  to  the  science. 

This  structural  work  has  been  supplemented  by  so  much 
classification  as  will  serve  to  make  clear  the  relationships  of 
different  groups,  and  the  principles  upon  which  the  classifica- 
tion is  based,  as  well  as  enable  the  student  to  recognize  the 
commoner  types  of  the  different  groups  as  they  are  met  with. 
The  aim  of  this  book  is  not,  however,  merely  the  identification 
of  plants.  We  wish  here  to  enter  a  strong  protest  against  the 

iii 


iv  PREFACE. 

only  too  prevalent  idea  that  the  chief  aim  of  botany  is  the 
ability  to  run  down  a  plant  by  means  of  an  "  Analytical  Key/7 
the  subject  being  exhausted  as  soon  as  the  name  of  the  plant 
is  discovered.  A  knowledge  of  the  plant  itself  is  far  more 
important  than  its  name,  however  desirable  it  may  be  to  know 
the  latter. 

In  selecting  the  plants  employed  as  examples  of  the  differ- 
ent groups,  such  were  chosen,  as  far  as  possible,  as  are  every- 
where common.  Of  course  this  was  not  always  possible,  as 
some  important  forms,  e.g.  the  red  and  brown  seaweeds,  are 
necessarily  not  always  readily  procurable  by  all  students,  but 
it  will  be  found  that  the  great  majority  of  the  forms  used,  or 
closely  related  ones,  are  within  the  reach  of  nearly  all  stu- 
dents ;  and  such  directions  are  given  for  collecting  and  pre- 
serving them  as  will  make  it  possible  even  for  those  in  the 
larger  cities  to  supply  themselves  with  the  necessary  mate- 
rials. Such  directions,  too,  for  the  manipulation  and  examina- 
tion of  specimens  are  given  as  will  make  the  book,  it  is  hoped, 
a  laboratory  guide  as  well  as  a  manual  of  classification.  Indeed, 
it  is  primarily  intended  that  the  book  should  so  serve  as  a  help 
in  the  study  of  the  actual  specimens. 

Although  much  can  be  done  in  the  study,  even  of  the  lowest 
plants,  without  microscopic  aid  other  than  a  hand  lens,  for  a 
thorough  understanding  of  the  structure  of  any  plant  a  good 
compound  microscope  is  indispensable,  and  wherever  it  is  pos- 
sible the  student  should  be  provided  with  such  an  instrument, 
to  use  this  book  to  the  best  advantage.  As,  however,  many 
are  not  able  to  have  the  use  of  a  microscope,  the  gross  anatomy 
of  all  the  forms  described  has  been  carefully  treated  for  the 
especial  benefit  of  such  students.  Such  portions  of  the  text, 
as  well  as  the  general  discussions,  are  printed  in  ordinary 
type,  while  the  minute  anatomy,  and  all  points  requiring 
microscopic  aid,  are  discussed  in  separate  paragraphs  printed 
in  smaller  type. 

The    drawings,  with  very  few  exceptions,   which  are  duly 


PREFACE.  V 

credited,  were  drawn  from  nature  by  the  author,  and  nearly 
all  expressly  for  this  work. 

A  list  of  the  most  useful  books  of  reference  is  appended,  all 
of  which  have  been  more  or  less  consulted  in  the  preparation 
of  the  following  pages. 

The  classification  adopted  is,  with  slight  changes,  that  given 
in  GoebePs  "  Outlines  of  Morphology  and  Classification  " ;  while, 
perhaps,  not  in  all  respects  entirely  satisfactory,  it  seems  to 
represent  more  nearly  than  any  other  our  present  knowledge 
of  the  subject.  Certain  groups,  like  the  Diatoms  and  Chara- 
cece,  are  puzzles  to  the  botanist,  and  at  present  it  is  impossible 
to  give  them  more  than  a  provisional  place  in  the  system. 

If  this  volume  serves  to  give  the  student  some  comprehen- 
sion of  the  real  aims  of  botanical  science,  and  its  claims  to  be 
something  more  than  the  "  Analysis  "  of  flowers,  it  will  have 
fulfilled  its  mission. 

DOUGLAS   H.    CAMPBELL. 

BLOOMINGTON,  INDIANA, 
October,  1889. 


TABLE   OF  CONTENTS. 


PAGE 

CHAPTER  I.  —  INTRODUCTION    .     . 1 

Composition  of  Matter ;  Biology  ;  Botany  ;  Zoology  ;  Depart- 
ments of  Botany ;  Implements  and  Reagents ;  Collecting 
Specimens. 

CHAPTER  II.  —  THE  CELL 6 

Parts  of  the  Cell ;  Formation  of  New  Cells ;  Tissues. 

CHAPTER  III.  —  CLASSIFICATION  OF  PLANTS 9 

Protophytes  ;  Slime-moulds  ;  Schizophytes  ;  Blue-green  Slimes, 
Oscillaria;    Schizomycetes,  Bacteria;   Green  Monads,   Eu- 
glena,  Volvox. 

CHAPTER  IV.  —  ALGJE 21 

Classification  of  Algae  ;  Green  Algae  ;  Protoooccacece,  Protococ- 
cus;  Confervacece,  Cladophora,  CEdogonium,  Coleochcete. 

CHAPTER  V.  —  GREEN  ALG^E  (Continued) 30 

Pond- scums,  Spirogyra;  Siphonece,  Vaucheria;  Characece, 
Chara. 

CHAPTER  VI. — BROWN  SEAWEEDS 41 

Diatomacece ;  True  Brown  Algae,  Fucus;  Classification  of 
Brown  Algae. 

CHAPTER  VII.  —  BED  ALG^E 49 

Structure  of  Red  Algae ;  Callithammon  ;  Fresh- Water  Forms. 


viil  BOTANY. 

PAGE 

CHAPTER  VIII.  —  FUNGI 54 

Phycomycetes,  Mycomycttes  ;    Phy  corny  cetes,    Black   Moulds, 
Mucor;  White  Rusts  and  Mildews,  Cystopus ;  Water  Moulds. 

CHAPTER  IX.  —  TRUE  FUNGI 63 

Yeast ;  Smuts  ;  A&comycetes ;  Dandelion  Mildew ;  Cup  Fungi, 
Ascobolus;  Lichens;  Black  Fungi. 

CHAPTER  X. — TRUE  FUNGI  (Continued) 77 

Basidiomycetes ;  Rusts;  Coprinus;  Classification. 

CHAPTER  XI.  —  BRYOPHYTES ,    .        86 

Classification  ;  Liverworts,  Madotheca  ;  Classification  of  Liver- 
worts ;  Mosses,  Funaria;  Classification  of  Mosses. 

CHAPTER  XII.  —  PTERIDOPHTTES .    ,    .  102 

Bryophytes  and  Pteridophytes  ;  Germination  and  Prothallium  ; 
Structure  of  Maiden- hair  Fern. 

CHAPTER  XIII.  —  CLASSIFICATION  OF  PTERIDOPHTTES    .  116 
Ferns  ;  Horse-tails ;  Club  Mosses. 

CHAPTER  XIV.  —  SPERMAPHYTES 128 

General    Characteristics ;    Gymnosperms   and    Angiosperms, 
Scotch-pine  ;  Classification  of  Gymnospenns. 

CHAPTER  XV.  —  SPERMAPHYTES  (Continued) 143 

Angiosperms;    Flowers  of    Angiosperms ;    Classification    of 
Angiosperms ;  Monocotyledons,  Structure  of  Erythranium. 

CHAPTER  XVI.  —  CLASSIFICATION  OF  MONOCOTYLEDONS    153 
Liliiflorw;  Enantioblastce  ;  Spadiciflorce  ;  Glumacece;  Scitam- 
inece;  Gynandrce,  Helobiw. 

CHAPTER  XVII. — DICOTYLEDONS      ........  170 

General  Characteristics  ;  Structure  of  Shepherd's-purse. 


TABLE  OF  CONTENTS.  ix 

PAGI 

CHAPTER    XVIII. — CLASSIFICATION    OF    DICOTYLEDONS  181 

Choripetalce :  luliflorce;  Centrospermce  ;  Apfianocyclce  ;  Eucy- 
clce;  Tricoccce;  Calyciflorce. 

CHAPTER    XIX.  —  CLASSIFICATION    OF    DICOTYLEDONS 
(Continued) 210 

Sympetalce:  Isocarpce,  Bicornes,  Primulince,  Diospyrince; 
Anisocarpce,  Tubiflorce,  Labiatiflorce,  Contvrtce,  Campanu- 
Zfnce,  Aggregate*. 

CHAPTER  XX.  —  FERTILIZATION  OF  FLOWERS    ....  225 

CHAPTER  XXI.  —  HISTOLOGICAL  METHODS 230 

Nuclear  Division  in  Wild  Onion ;  Methods  of  Fixing,  Staining, 
and  Mounting  Permanent  Preparations  ;  Reference  Books. 

INDEX  .  237 


BOTANY. 

CHAPTER  I. 

INTRODUCTION. 

ALL  matter  is  composed  of  certain  constituents  (about  sev- 
enty are  at  present  known),  which,  so  far  as  the  chemist  is 
concerned,  are  indivisible,  and  are  known  as  elements. 

Of  the  innumerable  combinations  of  these  elements,  two 
general  classes  may  be  recognized,  organic  and  inorganic  bodies. 
While  it  is  impossible,  owing  to  the  dependence  of  all  organ- 
ized matter  upon  inorganic  matter,  to  give  an  absolute  defini- 
tion, we  at  once  recognize  the  peculiarities  of  organic  or  living 
bodies  as  distinguished  from  inorganic  or  non-living  ones.  All 
living  bodies  feed,  grow,  and  reproduce,  these  acts  being  the 
result  of  the  action  of  forces  resident  within  the  organism. 
Inorganic  bodies,  on  the  other  hand,  remain,  as  a  rule,  un- 
changed so  long  as  they  are  not  acted  upon  by  external  forces. 

All  living  organisms  are  dependent  for  existence  upon  inor- 
ganic matter,  and  sooner  or  later  return  these  elements  to  the 
sources  whence  they  came.  Thus,  a  plant  extracts  from  the 
earth  and  air  certain  inorganic  compounds  which  are  converted 
by  the  activity  of  the  plant  into  a  part  of  its  own  substance, 
becoming  thus  incorporated  into  a  living  organism.  After  the 
plant  dies,  however,  it  undergoes  decomposition,  and  the  ele- 
ments are  returned  again  to  the  earth  and  atmosphere  from 
which  they  were  taken. 

Investigation  has  shown  that  living  bodies  contain  compara- 
tively few  elements,  but  these  are  combined  into  extraordina- 

1 


2  BOTANY. 

rily  complex  compounds.  The  following  elements  appear  to 
be  essential  to  all  living  bodies :  carbon,  hydrogen,  oxygen, 
nitrogen,  sulphur,  potassium.  Besides  these  there  are  several 
others  usually  present,  but  not  apparently  essential  to  all 
organisms.  These  include  phosphorus,  iron,  calcium,  sodium, 
magnesium,  chlorine,  silicon. 

As  we  examine  more  closely  the  structure  and  functions  of 
organic  bodies,  an  extraordinary  uniformity  is  apparent  in  all 
of  them.  This  is  disguised  in  the  more  specialized  forms,  but 
in  the  simpler  ones  is  very  apparent.  Owing  to  this  any 
attempt  to  separate  absolutely  the  animal  and  vegetable  king- 
doms proves  futile. 

The  science  that  treats  of  living  things,  irrespective  of  the 
distinction  between  plant  and  animal,  is  called  "  Biology,"  but 
for  many  purposes  it  is  desirable  to  recognize  the  distinctions, 
making  two  departments  of  Biology,  —  Botany,  treating  of 
plants ;  and  Zoology,  of  animals.  It  is  with  the  first  of  these 
only  that  we  shall  concern  ourselves  here. 

When  one  takes  up  a  plant  his  attention  is  naturally  first 
drawn  to  its  general  appearance  and  structure,  whether  it  is  a 
complicated  one  like  one  of  the  flowering  plants,  or  some  hum- 
bler member  of  the  vegetable  kingdom,  —  a  moss,  seaweed, 
toadstool,  —  or  even  some  still  simpler  plant  like  a  mould,  or 
the  apparently  structureless  green  scum  that  floats  on  a  stag- 
nant pond.  In  any  case  the  impulse  is  to  investigate  the  form 
and  structure  as  far  as  the  means  at  one's  disposal  will  permit. 
Such  a  study  of  structure  constitutes  "Morphology,"  which 
includes  two  departments,  —  gross  anatomy,  or  a  general  study 
of  the  parts ;  and  minute  anatomy,  or  "  Histology,"  in  which 
a  microscopic  examination  is  made  of  the  structure  of  the 
different  parts.  A  special  department  of  Morphology  called 
"Embryology"  is  often  recognized.  This  embraces  a  study 
of  the  development  of  the  organism  from  its  earliest  stage, 
and  also  the  development  of  its  different  members. 

From  a  study  of  the  structure  of  organisms  we  get  a  clue 


IN  TB  OD  UCTION.  3 

to  their  relationships,  and  upon  the  basis  of  such  relationships 
are  enabled  to  classify  them  or  unite  them  into  groups  so  as 
to  indicate  the  degree  to  which  they  are  related.  This  con- 
stitutes the  division  of  Botany  usually  known  as  Classification 
or  "  Systematic  Botany." 

Finally,  we  may  study  the  functions  or  workings  of  an 
organism  :  how  it  feeds,  breathes,  moves,  reproduces.  This  is 
"Physiology,"  and  like  classification  must  be  preceded  by  a 
knowledge  of  the  structures  concerned. 

For  the  study  of  the  gross  anatomy  of  plants  the  following 
articles  will  be  found  of  great  assistance  :  1,  a  sharp  knife, 
and  for  more  delicate  tissues,  a  razor ;  2.  a  pair  of  small,  fine- 
pointed  scissors ;  3.  a  pair  of  mounted  needles  (these  can  be 
made  by  forcing  ordinary  sewing  needles  into  handles  of  pine 
or  other  soft  wood)  ;  4.  a  hand  lens ;  5.  drawing-paper  and 
pencil,  and  a  note  book. 

For  the  study  of  the  lower  plants,  as  well  as  the  histology 
of  the  higher  ones,  a  compound  microscope  is  indispensable. 
Instruments  with  lenses  magnifying  from  about  20  to  500 
diameters  can  be  had  at  a  cost  varying  from  about  $20  to  $30, 
and  are  sufficient  for  any  ordinary  investigations. 

Objects  to  be  studied  with  the  compound  microscope  are  usu- 
ally examined  by  transmitted  light,  and  must  be  transparent 
enough  to  allow  the  light  to  pass  through.  The  objects  are 
placed  upon  small  glass  slips  (slides),  manufactured  for  the 
purpose,  and  covered  with  extremely  thin  plates  of  glass,  also 
specially  made.  If  the  body  to  be  examined  is  a  large  one, 
thin  slices  or  sections  must  be  made.  This  for  most  purposes 
may  be  done  with  an  ordinary  razor.  Most  plant  tissues  are 
best  examined  ordinarily  in  water,  though  of  course  specimens 
so  mounted  cannot  be  preserved  for  any  length  of  time.1 

In  addition  to  the  implements  used  in  studying  the  gross 
anatomy,  the  following  will  be  found  useful  in  histological 

1  For  the  mounting  of  permanent  preparations,  see  Chapter  XIX. 


4  BOTANY. 

work:  1.  a  small  camel's-hair  brush  for  picking  up  small 
sections  and  putting  water  in  the  slides ;  2.  small  forceps  for 
handling  delicate  objects ;  3.  blotting  paper  for  removing  super- 
fluous water  from  the  slides  and  drawing  fluids  under  the  cover 
glass ;  4.  pieces  of  elder  or  sunflower  pith,  for  holding  small 
objects  while  making  sections. 

In  addition  to  these  implements,  a  few  reagents  may  be 
recommended  for  the  simpler  histological  work.  The  most 
important  of  these  are  alcohol,  glycerine,  potash  (a  strong  solu- 
tion of  potassium  hydrate  in  water),  iodine  (either  a  little  of 
the  commercial  tincture  of  iodine  in  water,  or,  better,  a  solution 
of  iodine  in  iodide  of  potassium),  acetic  acid,  and  some  stain- 
ing fluid.  (An  aqueous  or  alcoholic  solution  of  gentian  violet 
or  methyl  violet  is  one  of  the  best.) 

A  careful  record  should  be  kept  by  the  student  of  all  work 
done,  both  by  means  of  written  notes  and  drawings.  For  most 
purposes  pencil  drawings  are  most  convenient,  and  these  should 
be  made  with  a  moderately  soft  pencil  on  unruled  paper.  If 
it  is  desired  to  make  the  drawings  with  ink,  a  careful  outline 
should  first  be  made  with  a  hard  pencil  and  this  inked  over 
with  India-ink  or  black  drawing  ink.  Ink  drawings  are  best 
made  upon  light  bristol  board  with  a  hard,  smooth-finished 
surface. 

When  obtainable,  the  student  will  do  best  to  work  with 
freshly  gathered  specimens  ;  but  as  these  are  not  always  to  be 
had  when  wanted,  a  few  words  about  gathering  and  preserving 
material  may  be  of  service. 

Most  of  the  lower  green  plants  (algce)  may  be  kept  for  a 
long  time  in  glass  jars  or  other  vessels,  provided  care  is  taken 
to  remove  all  dead  specimens  at  first  and  to  renew  the  water 
from  time  to  time.  They  usually  thrive  best  in  a  north  win- 
dow where  they  get  little  or  no  direct  sunshine,  and  it  is  well 
to  avoid  keeping  them  too  warm. 

Numbers  of  the  most  valuable  fungi  —  i.e.  the  lower  plants 
that  are  not  green  —  grow  spontaneously  on  many  organic 


INTRODUCTION.  5 

substances  that  are  kept  warm  and  moist.  Fresh  bread  kept 
moist  and  covered  with  a  glass  will  in  a  short  time  produce  a 
varied  crop  of  moulds,  and  fresh  horse  manure  kept  in  the 
same  way  serves  to  support  a  still  greater  number  of  fungi. 

Mosses,  ferns,  etc.,  can  be  raised  with  a  little  care,  and  of 
course  very  many  flowering  plants  are  readily  grown  in  pots. 

Most  of  the  smaller  parasitic  fungi  (rusts,  mildews,  etc.) 
may  be  kept  dry  for  any  length  of  time,  and  on  moistening 
with  a  weak  solution  of  caustic  potash  will  serve  nearly  as 
well  as  freshly  gathered  specimens  for  most  purposes. 

When  it  is  desired  to  preserve  as  perfectly  as  possible  the 
more  delicate  plant  structures  for  future  study,  strong  alcohol 
is  the  best  and  most  convenient  preserving  agent.  Except  for 
loss  of  color  it  preserves  nearly  all  plant  tissues  perfectly. 


CHAPTER   II. 


THE   CELL. 

IF  we  make  a  thin  slice  across  the  stem  of  a  rapidly  growing 
plant,  —  e.g.  geranium,  begonia,  celery,  —  mount  it  in  water, 
and  examine  it  microscopically,  it  will  be  found  to  be  made  up 
of  numerous  cavities  or  chambers  separated  by  delicate  parti- 
tions. Often  these  cavities  are  of  sufficient  size  to  be  visible 
to  the  naked  eye,  and  examined  with  a  hand  lens  the  section 
appears  like  a  piece  of  fine  lace,  each  mesh  being  one  of  the 
chambers  visible  when  more  strongly  magnified.  These  cham- 
bers are  known  as  "cells,"  and  of  them  the  whole  plant  is 
built  up. 

In  order  to  study  the  structure  of  the  cell  more  exactly  we  will  select 
such  as  may  be  examined  without  cutting  them.  A  good  example  is 

furnished  by  the  common  spiderwort 
(Fig.  1).  Attached  to  the  base  of  the 
stamens  (Fig.  85,  B)  are  delicate  hairs 
composed  of  chains  of  cells,  which  may 
be  examined  alive  by  carefully  remov- 
ing a  stamen  and  placing  it  in  a  drop  of 
water  under  a  cover  glass.  Each  cell 
(Fig.  1 )  is  an  oblong  sac,  with  a  deli- 
cate colorless  wall  which  chemical  tests 
show  to  be  composed  of  cellulose,  a 
substance  closely  resembling  starch. 
Within  this  sac,  and  forming  a  lining 
to  it,  is  a  thin  layer  of  colorless  matter 
containing  many  fine  granules.  Bands 
and  threads  of  the  same  substance 
traverse  the  cavity  of  the  cell,  which 
is  filled  with  a  deep  purple  homoge- 
neous fluid.  This  fluid,  which  in  most  cells  is  colorless,  is  called  the 
cell  sap,  and  is  composed  mainly  of  water.  Imbedded  in  the  granular 
6 


— w 


"pr. 


FIG.  1.—  A  single  cell  from  a  hair 
on  the  stamen  of  the  common 
spiderwort  (Tradescantia), 
x  150.  pr.  protoplasm;  w,  cell 
wall;  n,  nucleus. 


THE  CE±L. 


n—  — . 


FIG.  2.  —  An  Amwba.  A  cell 
without  a  cell  wall,  n,  nu- 
cleus ;  v,  vacuoles,  x  300. 


lining  of  the  sac  is  a  roundish  body  (n),  which  itself  has  a  definite 
membrane,  and  usually  shows  one  or  more  roundish  bodies  within, 
besides  an  indistinctly  granular  appearance.  This  body  is  called  the 
nucleus  of  the  cell,  and  the  small  one  within  it,  the  nucleolus. 

The  membrane  surrounding  the  cell  is  known  as  the  cell  wall,  and  in 
young  plant  cells  is  always  composed  of  cellulose. 

The  granular  substance  lining  the  cell  wall  (Fig.  1,  pr.)  is  called  "pro- 
toplasm," and  with  the  nucleus  constitutes 
the  living  part  of  the  cell.  If  sufficiently 
magnified,  the  granules  within  the  proto- 
plasm will  be  seen  to  be  in  active  streaming 
motion.  This  movement,  which  is  very  evi- 
dent here,  is  not  often  so  conspicuous,  but 
still  may  often  be  detected  without  difficulty. 

The  cell  may  be  regarded  as  the 
unit  of  organic  structure,  and  of 
cells  are  built  up  all  of  the  complicated  structures  of  which 
the  bodies  of  the  highest  plants  and  animals  are  composed. 
We  shall  find  that  the  cells  may  become  very  much  modified 
for  various  purposes,  but  at 
first  they  are  almost  identical 
in  structure,  and  essentially  the 
same  as  the  one  we  have  just 
considered. 

Very  many  of  the  lower  forms 
of  life  consist  of.  but  a  single 
cell  which  may  occasionally  be 
destitute  of  a  cell  wall.  Such 
a  form  is  shown  in  Figure  2. 
Here  we  have  a  mass  of  proto-  T 

FIG.  3.  —  Hairs  from  the  leaf  stalk  of 
plasm  with  a  nucleus  (n)  and 

cavities  (vacuoles,  v)  filled  with 
cell  sap,  but  no  cell  wall.  The 
protoplasm  is  in  constant  move- 
ment, and  by  extensions  of  a 
portion  of  the  mass  and  contraction  of  other  parts,  the  whole 
creeps  slowly  along.  Other  naked  cells  (Fig.  12,  B ;  Fig.  16,  <7) 


a  wild  geranium.  A,  single-celled 
hair.  B  and  (7,  hairs  consisting 
of  a  row  of  cells.  The  terminal 
rounded  cell  secretes  a  peculiar 
scented  oil  that  gives  the  plant  its 
characteristic  odor.  .#,  x  50;  C, 
x  150. 


BOTANY. 


are  provided  with  delicate  thread-like  processes  of  protoplasm 
called  "cilia"  (sing,  cilium),  which  are  in  active  vibration, 
and  propel  the  cell  through  the  water. 

_  On  placing  a  cell  into  a  fluid 

A 

Ooooooo 


denser  than  the  cell  sap  (e.g.  a 
ten-per-cent  solution  of  sugar  in 
water),  a  portion  of  the  water 
will  be  extracted  from  the  cell, 
and  we  shall  then  see  the  proto- 
plasm receding  from  the  wall 
(Fig.  4,  O),  showing  that  it  is 
normally  in  a  state  of  tension 
due  to  pressure  from  within  of 
the  cell  sap.  The  cell  wall 
shows  the  same  thing  though 
in  a  less  degree,  owing  to  its 
being  much  more  rigid  than  the 
protoplasmic  lining.  It  is  owing 
to  the  partial  collapsing  of  the 
cells,  consequent  on  loss  of 
™ter,  that  plants  wither  When 

mum,  showing  its  cellular  structure.  Ep.,  the  supply  of  water  is  cut  off. 
epidermis,    h,  a  hair,    x  50.     C,  a  cell 

from  the  prothallium  (young  plant)  of  a         As   Cells  grow,  new  ones 
fern,  x  150.   The  contents  of  the  cell  con-  ,°         '. 

tracted  by  the  action  of  a  solution  of  are  formed  in  various  ways. 

If    the    new    cells   remain 

together,  cell  aggregates,  called  tissues,  are  produced,  and  of 
these  tissues  are  built  up  the  various  organs  of  the  higher 
plants.  The  simplest  tissues  are  rows  of  cells,  such  as  form  the 
hairs  covering  the  surface  of  the  organs  of  many  flowering 
plants  (Fig.  3),  and  are  due  to  a  division  of  the  cells  in  a 
single  direction.  If  the  divisions  take  place  in  three  planes, 
masses  of  cells,  such  as  make  up  the  stems,  etc.,  of  the  higher 
plants,  result  (Fig.  4,  A,  B) . 


CHAPTER  III. 

CLASSIFICATION   OF   PLANTS.  —  PROTOPHYTES. 

FOR  the  sake  of  convenience  it  is  desirable  to  collect  into 
groups  such  plants  as  are  evidently  related;  but  as  our  knowl- 
edge of  many  forms  is  still  very  imperfect,  any  classification 
we  may  adopt  must  be  to  a  great  extent  only  provisional,  and 
subject  to  change  at  any  time,  as  new  forms  are  discovered  or 
others  become  better  understood. 

The  following  general  divisions  are  usually  accepted :  I. 
Sub-kingdom  (or  Branch)  ;  II.  Class ;  III.  Order ;  IV.  Family ; 
V.  Genus;  VI.  Species. 

To  illustrate :  The  white  pine  belongs  to  the  highest  great 
division  (sub-kingdom)  of  the  plant  kingdom.  The  plants  of 
this  division  all  produce  seeds,  and  hence  are  called  "  sperma- 
phytes"  ("seed  plants").  They  may  be  divided  into  two 
groups  (classes),  distinguished  by  certain  peculiarities  in  the 
flowers  and  seeds.  These  are  named  respectively  "gymno- 
sperms  "  and  "  angiosperms,"  and  to  the  first  our  plant  belongs. 
The  gymnosperms  may  be  further  divided  into  several  subor- 
dinate groups  (orders),  one  of  which,  the  CQnifers,  or  cone-bear- 
ing evergreens,  includes  our  plant.  This  order  includes  several 
families,  among  them  the  fir  family  (Abietinece),  including  the 
pines  and  firs.  Of  the  sub-divisions  (genera,  sing,  genus)  of 
the  fir  family,  one  of  the  most  familiar  is  the  genus  Pinus, 
which  embraces  all  the  true  pines.  Comparing  different  kinds 
of  pines,  we  find  that  they  differ  in  the  form  of  the  cones,  ar- 
rangement of  the  leaves,  and  other  minor  particulars.  The  form 
we  have  selected  differs  from  all  other  native  forms  in  its  cones, 
and  also  in  having  the  leaves  in  fives,  instead  of  twos  or  threes, 
as  in  most  other  kinds.  Therefore  to  distinguish  the  white  pine 
from  all  other  pines,  it  is  given  a  "  specific  "  name,  strobus. 


10  BOTANY. 

The  following  table  will  show  more  plainly  what  is  meant 


Includes  all  spermaphytes,  or  seed  plants. 


1    S 


All  naked-seeded  plants. 


All  cone-bearing  evergreens. 

i* 

I   1? 


Firs,  Pines,  etc. 


=3    8 

s  I 


Pines. 

If 

o     o 


White  Pine. 


CLASSIFICATION  OF  PLANTS. 


11 


SUB-KINGDOM   I. 
PROTOPHYTES. 

The  name  Protophytes  (Protopliyta)  has  been  applied  to  a 
large  number  of  simple  plants,  which  differ  a  good  deal  among 
themselves.  Some  of  them  differ  strikingly  from  the  higher 
plants,  and  resemble  so  remarkably  certain  low  forms  of  animal 

A 


FIG.  5.  —  A,  a  portion  of  a  slime  mould  growing  on  a  bit  of  rotten  wood,  x  3. 
B,  outline  of  a  part  of  the  same,  x  25.  C,  a  small  portion  showing  the  densely 
granular  character  of  the  protoplasm,  x  150.  D,  a  group  of  spore  cases 
of  a  slime  mould  ( Trichia) ,  of  about  the  natural  size.  E,  two  spore  cases, 
x  5.  The  one  at  the  right  has  begun  to  open.  F,  a  thread  (capillitium)  and 
spores  of  Trichia,  x  50.  G,  spores.  //,  end  of  the  thread,  x  300.  /,  zoospores 
of  Trichia,  x  300.  i,  ciliated  form;  n,  amoeboid  forms,  n,  nucleus,  v, 
contractile  vacuole.  J,  K,  sporangia  of  two  common  slime  moulds.  J,  Stern- 
onitis,  x  2.  Jf,  Arcyria,  x  4. 

life  as  to  be  quite  indistinguishable  from  them,  at  least  in  cer- 
tain stages.  Indeed,  there  are  certain  forms  that  are  quite  as 
much  animal  as  vegetable  in  their  attributes,  and  must  be 
regarded  as  connecting  the  two  kingdoms.  Such  forms  are 


12  BOTANY. 

the  slime  moulds  (Fig.  5),  Euglena  (Fig.  9),  Volvox  (Fig.  10), 
and  others. 

Other  protophytes,  while  evidently  enough  of  vegetable  nat- 
ure, are  nevertheless  very  different  in  some  respects  from  the 
higher  plants. 

The  protophytes  may  be  divided  into  three  classes :  I.  The 
slime  moulds  (Myxomycetes)  ;  II.  The  Schizophytes ;  III. 
The  green  monads  (  Volvocinece) . 

CLASS  I. — THE  SLIME  MOULDS. 

These  curious  organisms  are  among  the  most  puzzling  forms 
with  which  the  botanist  has  to  do,  as  they  are  so  much  like  some 
of  the  lowest  forms  of  animal  life  as  to  be  scarcely  distinguish- 
able from  them,  and  indeed  they  are  sometimes  regarded  as  ani- 
mals rather  than  plants.  At  certain  stages  they  consist  of 
naked  masses  of  protoplasm  of  very  considerable  size,  not  infre- 
quently several  centimetres  in  diameter.  These  are  met  with  on 
decaying  logs  in  damp  woods,  on  rotting  leaves,  and  other  decay- 
ing vegetable  matter.  The  commonest  ones  are  bright  yellow 
or  whitish,  and  form  soft,  slimy  coverings  over  the  substratum 
(Fig.  5,  A),  penetrating  into  its  crevices  and  showing  sensi- 
tiveness toward  light.  The  plasmodium,  as  the  mass  of  pro- 
toplasm is  called,  may  be  made  to  creep  upon  a  slide  in  the 
following  way :  A  tumbler  is  rilled  with  water  and  placed  in  a 
saucer  filled  with  sand.  A  strip  of  blotting  paper  about  the 
width  of  the  slide  is  now  placed  with  one  end  in  the  water, 
the  other  hanging  over  the  edge  of  the  glass  and  against  one 
side  of  a  slide,  which  is  thus  held  upright,  but  must  not  be 
allowed  to  touch  the  side  of  the  tumbler.  The  strip  of .  blot- 
ting paper  sucks  up  the  water,  which  flows  slowly  down  the 
surface  of  the  slide  in  contact  with  the  blotting  paper.  If  now 
a  bit  of  the  substance  upon  which  the  plasmodium  is  growing 
is  placed  against  the  bottom  of  the  slide  on  the  side  where  the 
stream  of  water  is,  the  protoplasm  will  creep  up  against  the 


CLASSIFICATION   OF  PLANTS.  13 

current  of  water  and  spread  over  the  slide,  forming  delicate 
threads  in  which  most  active  streaming  movements  of  the  cen- 
tral granular  protoplasm  may  be  seen  under  the  microscope, 
and  the  ends  of  the  branches  may  be  seen  to  push  forward 
much  as  we  saw  in  the  amoeba.  In  order  that  the  experiment 
may  be  successful,  the  whole  apparatus  should  be  carefully 
protected  from  the  light,  and  allowed  to  stand  for  several 
hours.  This  power  of  movement,  as  well  as  the  power  to  take 
in  solid  food,  are  eminently  animal  characteristics,  though  the 
former  is  common  to  many  plants  as  well. 

After  a  longer  or  shorter  time  the  mass  of  protoplasm  con- 
tracts and  gathers  into  little  heaps,  each  of  which  develops  into 
a  structure  that  has  no  resemblance  to  any  animal,  but  would 
be  at  once  placed  with  plants.  In  one  common  form  (Trichia) 
these  are  round  or  pear-shaped  bodies  of  a  yellow  color,  and 
about  as  big  as  a  pin  head  (Fig.  5,  /)),  occurring  in  groups 
on  rotten  logs  in  damp  woods.  Others  are  stalked  (Arcyria, 
/Stemonitis)  (Fig.  5,  J,  K),  and  of  various  colors,  —  red,  brown, 
etc.  The  outer  part  of  the  structure  is  a  more  or  less  firm 
wall,  which  breaks  when  ripe,  discharging  a  powdery  mass, 
mixed  in  most  forms  with  very  fine  fibres. 

When  strongly  magnified  the  fine  dust  is  found  to  be  made  up  of  in- 
numerable small  cells  with  thick  walls,  marked  with  ridges  or  processes 
which  differ  much  in  different  species.  The  fibres  also  differ  much  in 
different  genera.  Sometimes  they  are  simple,  hair-like  threads ;  in 
others  they  are  hollow  tubes  with  spiral  thickenings,  often  very  regu- 
larly placed,  running  around  their  walls. 

The  spores  may  sometimes  be  made  to  germinate  by  placing  them  in 
a  drop  of  water,  and  allowing  them  to  remain  in  a  warm  place  for  about 
twenty-four  hours.  If  the  experiment  has  been  successful,  at  the  end  of 
this  time  the  spore  membrane  will  have  burst,  and  the  contents  escaped 
in  the  form  of  a  naked  mass  of  protoplasm  (Zoospore)  with  a  nucleus, 
and  often  showing  a  vacuole  (Fig.  5,  -u),  that  alternately  becomes  much 
distended,  and  then  disappears  entirely.  On  first  escaping  it  is  usually 
provided  with  a  long,  whip-like  filament  of  protoplasm,  which  is  in  active 
movement,  and  by  means  of  which  the  cell  swims  actively  through  the 
water  (Fig.  5,  / 1).  Sometimes  such  a  cell  will  be  seen  to  divide  into  two, 


14  BOTANY. 

the  process  taking  but  a  short  time,  so  that  the  numbers  of  these  cells 
under  favorable  conditions  may  become  very  large.  After  a  time  the  lash 
is  withdrawn,  and  the  cell  assumes  much  the  form  of  a  small  amoeba  (/  u). 

The  succeeding  stages  are  difficult  to  follow.  After  repeat- 
edly dividing,  a  large  number  of  these  amoeba-like  cells  run  to- 
gether, coalescing  when  they  come  in  contact,  and  forming  a 
mass  of  protoplasm  that  grows,  and  finally  assumes  the  form 
from  which  it  started. 

Of  the  common  forms  of  slime  moulds  the  species  of  Trichia  (Figs.  Z), 
I)  and  Physarum  are,  perhaps,  the  best  for  studying  the  germination,  as 
the  spores  are  larger  than  in  most  other  forms,  and  germinate  more 
readily.  The  experiment  is  apt  to  be  most  successful  if  the  spores  are 
sown  in  a  drop  of  water  in  which  has  been  infused  some  vegetable  matter, 
such  as  a  bit  of  rotten  wood,  boiling  thoroughly  to  kill  all  germs.  A  drop 
of  this  fluid  should  be  placed  on  a  perfectly  clean  cover  glass,  which  it  is 
well  to  pass  once  or  twice  through  a  flame,  and  the  spores  transferred  to 
this  drop  with  a  needle  previously  heated.  By  these  precautions  foreign 
germs  will  be  avoided,  which  otherwise  may  interfere  seriously  with  the 
growth  of  the  young  slime  moulds.  After  sowing  the  spores  in  the  drop 
of  culture  fluid,  the  whole  should  be  inverted  over  a  so-called  "moist 
chamber."  This  is  simply  a  square  of  thick  blotting  paper,  in  which  an 
opening  is  cut  small  enough  to  be  entirely  covered  by  the  cover  glass,  but 
large  enough  so  that  the  drop  in  the  centre  of  the  cover  glass  will  not 
touch  the  sides  of  the  chamber,  but  will  hang  suspended  clear  in  it.  The 
blotting  paper  should  be  soaked  thoroughly  in  pure  water  (distilled  water 
is  preferable),  and  then  placed  on  a  slide,  covering  carefully  with  the  cover 
glass  with  the  suspended  drop  of  fluid  containing  the  spores.  The  whole 
should  be  kept  under  cover  so  as  to  prevent  loss  of  water  by  evaporation. 
By  this  method  the  spores  may  be  examined  conveniently  without  disturb- 
ing them,  and  the  whole  may  be  kept  as  long  as  desired,  so  long  as  the 
blotting  paper  is  kept  wet,  so  as  to  prevent  the  suspended  drop  from 
drying  up. 

CLASS  II.  —  Scltizophytes. 

The  Schizophytes  are  very  small  plants,  though  not  infre- 
quently occurring  in  masses  of  considerable  size.  They  are 
among  the  commonest  of  all  plants,  and  are  found  everywhere. 
They  multiply  almost  entirely  by  simple  transverse  division,  or 


CLASSIFICATION   OF  PLANTS. 


15 


splitting  of  the  cells,  whence  their  name.  There  are  two  pretty 
well-marked  orders,  —  the  blue-green  slimes  (Cyanophycece)  and 
the  bacteria  (Schizomycetes) .  They  are  distinguished,  primarily, 
by  the  first  (with  a  very  few  exceptions)  containing  chlorophyll 
(leaf -green),  which  is  entirely  absent  from  nearly  all  of  the 
latter. 

The  blue-green  slimes  :  These  are,  with  few  exceptions,  green 
plants  of  simple  structure,  but  possessing,  in  addition  to  the 
ordinary  green  pigment  (chlorophyll,  or  leaf -green),  another 
coloring  matter,  soluble  in  water,  and  usually  blue  in  color, 
though  sometimes  yellowish  or  red. 

As  a  representative  of  the  group,  we  will  select  one  of  the 
commonest  forms  (Oscillaria) ,  known  sometimes  as  green  slime, 
from  forming  a  dark  blue-green  or  blackish  slimy  coat  over  the 
mud  at  the  bottom  of  stagnant  or  sluggish  water,  in  watering 
troughs,  on  damp  rocks,  or  even  on  moist  earth.  A  search  in 
the  places  mentioned  can  hardly  fail  to  secure  plenty  of  speci- 
mens for  study.  If  a  bit  of  the  slimy  mass  is  transferred  to 
a  china,  dish,  or  placed  with  con- 
siderable water  on  a  piece  of  stiff 
paper,  after  a  short  time  the  edge 
of  the  mass  will  show  numerous 
extremely  fine  filaments  of  a  dark 
blue-green  color,  radiating  in  all 
directions  from  the  mass  (Fig. 
6,  a).  The  filaments  are  the  in- 
dividual plants,  and  possess  con- 
siderable power  of  motion,  as  is 
shown  by  letting  the  mass  re- 
main undisturbed  for  a  day  or 
two,  at  the  end  of  which  time 
they  will  have  formed  a  thin 
film  over  the  surface  of  the  vessel  in  which  they  are  kept; 
and  the  radiating  arrangement  of  the  filaments  can  then  be 
plainly  seen.  * 


FIG.  G.  —  Blue-green  slime  (Oscil- 
laria). A,  mass  of  filaments  of 
the  natural  size.  B,  single  fila- 
ment, x  300.  C,  a  piece  of  a  fila- 
ment that  has  become  separated. 
s,  sheath,  x  300. 


16  BOTANY. 

If  the  mass  is  allowed  to  dry  on  the  paper,  it  often  leaves  a 
bright  blue  stain,  due  to  the  blue  pigment  in  the  cells  of  the 
filament.  This  blue  color  can  also  be  extracted  by  pulverizing 
a  quantity  of  the  dried  plants,  and  pouring  water  over  them, 
the  water  soon  becoming  tinged  with  a  decided  blue.  If  now 
the  water  containing  the  blue  pigment  is  filtered,  and  the  resi- 
due treated  with  alcohol,  the  latter  will  extract  the  chlorophyll, 
becoming  colored  of  a  yellow-green. 

The  microscope  shows  that  the  filaments  of  which  the  mass  is  com- 
posed (Fig.  6,  B)  are  single  rows  of  short  cylindrical  cells  of  uniform 
diameter,  except  at  the  end  of  the  filament,  where  they  usually  become 
somewhat  smaller,  so  that  the  tip  is  more  or  less  distinctly  pointed.  The 
protoplasm  of  the  cells  has  a  few  small  granules  scattered  through  it,  and 
is  colored  uniformly  of  a  pale  blue-green.  No  nucleus  can  be  seen. 

If  the  filament  is  broken,  there  may  generally  be  detected  a  delicate, 
colorless  sheath  that  surrounds  it,  and  extends  beyond  the  end  cells 
(Fig.  6,  c) .  The  filament  increases  in  length  by  the  individual  cells  under- 
going division,- this  always  taking  place  at  right  angles  to  the  axis  of  the 
filament.  New  filaments  are  produced  simply  by  the  older  ones  breaking 
into  a  number  of  pieces,  each  of  which  rapidly  grows  to  full  size. 

The  name  "  oscillaria "  arises  from  the  peculiar  oscillating 
or  swinging  movements  that  the  plant  exhibits.  The  most 
marked  movement  is  a  swaying  from  side  to  side,  combined 
with  a  rotary  motion  of  the  free  ends  of  the  filaments,  which 
are  often  twisted  together  like  the  strands  of  a  rope.  If  the 
filaments  are  entirely  free,  they  may  often  be  observed  to  move 
forward  with  a  slow,  creeping  movement.  Just  how  these 
movements  are  caused  is  still  a  matter  of  controversy. 

The  lowest  of  the  Cyanophycece  are  strictly  single-celled,  sep- 
arating as  soon  as  formed,  but  cohering  usually  in  masses  or 
colonies  by  means  of  a  thick  mucilaginous  substance  that  sur- 
rounds them  (Fig.  7,  Z>). 

The  higher  ones  are  filaments,  in  which  there  may  be  con- 
siderable differentiation.  These  often  occur  in  masses  of  con- 
siderable size,  forming  jelly-like  lumps,  which  may  be  soft  or 
quite  firm  (Fig.  7,  A,  B).  Th*y  are  sometimes  found  on 


CLASSIFICATION   OF  PLANTS. 


17 


damp  ground,  but  more  commonly  attached  to  plants,  stones, 
etc.,  in  water.  The  masses  vary  in  color  from  light  brown 
to  deep  blackish  green,  and  in  size  from  that  of  a  pin  head  to 
several  centimetres  in  diameter. 

In  the  higher  forms  special  cells  called  heterocysts  are 
found.  They  are  colorless,  or  light  yellowish,  regularly  dis- 
posed ;  but  their  function  is  not  known.  Besides  these,  cer- 
tain cells  become  thick-walled,  and  form  resting  cells  (spores) 


FIG.  7.  —  Forms  of  CyanophycesR.  A,  Nostoc.  B,  Glueotrichia,  x  1.  C,  in- 
dividual of  Glwotrichia.  D,  Chroococcus.  E,  Nostoc.  F,  Oscillaria.  G, 
H,  Tolypothrix.  All  x  300.  y,  heterocyst.  sp.  spore. 


the  propagation  of  the  plant  (Fig.  7,  G.  sp).  In  species 
where  the  sheath  of  the  filament  is  well  marked  (Fig.  7,  H), 
groups  of  cells  slip  out  of  the  sheath,  and  develop  a  new  one, 
thus  giving  rise  to  a  new  plant. 

The  bacteria  (Schizomycetes),  although  among  the  commonest 
of  organisms,  owing  to  their  excessive  minuteness,  are  difficult 
to  study,  especially  for  the  beginner.  They  resemble,  in  their 
general  structure  and  methods  of  reproduction,  the  blue-green 
slimes,  but  a^e,  with  very  few  exceptions,  destitute  of  chloro- 
phyll, although  often  possessing  bright  pigments,  —  blue,  vio- 

*&L  red,  etc.  It  is  one  of  these  that  sometimes  forms  blood- 
rm.  spots  in  flour  paste  or  bits*  of  bread  that  have  been  kept 
very  moist  and  warm.  They  are  universally  present  where 

decomposition  is  going  on,  and  are  themselves  the  principal 


18  BOTANY. 

agents  of  decay,  which  is  the  result  of  their  feeding  upon  the 
substance,  as,  like  all  plants  without  chlorophyll,  they  require 
organic  matter  for  food.  Most  of  the  species  are  very  tenacious 
of  life,  and  may  be  completely  dried  up  for  a  long  time  with- 
out dying,  and  on  being  placed  in  water  will  quickly  revive. 
Being  so  extremely  small,  they  are  readily  carried  about  in 
the  air  in  their  dried-up  condition,  and  thus  fall  upon  exposed 
bodies,  setting  up  decomposition  if  the  conditions  are  favor- 
able. 

A  simple  experiment  to  show  this  may  be  performed  by 
taking  two  test  tubes  and  partly  filling  them  with  an  infusion 
of  almost  any  organic  substance  (dried  leaves  or  hay,  or  a  bit 
of  meat  will  answer).  The  fluid  should  now  be  boiled  so  as 
to  kill  any  germs  that  may  be  in  it  ;  and  while  hot,  one  of  the 
vessels  should  be  securely  stopped  up  with  a  plug  of  cotton 
wool,  and  the  other  left  open.  The  cotton  prevents  access  of 
all  solid  particles,  but  allows  the  air  to  enter.  If  proper  care 
has  been  taken,  the  infusion  in  the  closed  vessel  will  remain 
unchanged  indefinitely  ;  but  the  other  will  soon  become  turbid, 
and  a  disagreeable  odor  will  be  given  off.  Microscopic  exami- 
nation shows  the  first  to  be  free  from  germs 
of  any  kind,  while  the  second  is  swarming> 
with  various  forms  of  bacteria. 

These  little  organisms  have  of  late  years 
attracted  the  attention  of  very  many  scien- 
tists,  from  the  fact  that  to  them  is  due  many,  -* 
if  not  all,  contagious  diseases.     The  germs 
of  many  such  diseases  have  been  isolated, 
and  experiments  prove  beyond  doubt  that 
these  are  alone  the   causes  of  the  diseases  % 
in  question. 


F      «  —  B    t    •  ^   a  drop  of  water    containing  bacteria  is  gx- 

amined,  we  find  them  to  be  excessively  small,  many 

of  them  barely  visible  with  the  strongest  lenses.     The  larger  ones  (Fig.  8) 
recall  quite  strongly  the  smaller  species  of  oscillaria,  and  exhibit  similO 


CLASSIFICATION  OF  PLANTS. 


19 


movements.     Others  are  so  small  as  to  appear  as  mere  lines  and  dots, 
even  with  the  strongest  lenses.     Among  the  common  forms  are   small, 
nearly  globular  cells ;   oblong,    rod- 
shaped  or  thread- shaped  filaments, 
either  straight  or  curved,  or  even  spi- 
rally twisted.    Frequently  they  show 
a  quick  movement  which  is  probably 
in  all  cases  due  to  cilia,  which  are, 
however,  too  small  to  be  seen  in  most 
cases. 


Reproduction  is  for  the  most 
part  by  simple  transverse  divis- 
ion, as  in  oscillaria;  but  occa- 
sionally spores  are  produced 
also. 


FIG.  9.  —  Euglena.  A ,  individual  in 
the  active  condition.  E,  the  red 
"  eye-spot."  c,  flagellum.  n,  nu- 
cleus. B,  resting  stage.  C',  indi- 
vidual dividing,  x  300. 


CLASS  III.  —  GREEN  MONADS  (  Volvocinece) . 

This  group  of  the  protophytes  is  unquestionably  closely  re- 
lated to  certain  low  animals  (Monads  or  Flagellata),  with  which 
they  are  sometimes  united.  They  are  characterized  by  being 
actively  motile,  and  are  either  strictly  unicellular,  or  the  cells  are 
united  by  a  gelatinous  envelope  into  a  colony  of  definite  form. 

Of  the  first  group,  Euglena  (Fig.  9),  may  be  selected  as  a  type. 

This  organism  is  found  frequently  among  other  algse,  and  occasion- 
ally forms  a  green  film  on  stagnant  water.  It  is  sometimes  regarded  as 
a  plant,  sometimes  as  an  animal,  and  is  an  elongated,  somewhat  worm- 
like  cell  without  a  definite  cell  wall,  so  that  it  can  change  its  form  to  some 
extent.  The  protoplasm  contains  oval  masses,  which  are  bright  green  in 
color ;  but  the  forward  pointed  end  of  the  cell  is  colorless,  and  has  a  little 
depression.  At  this  end  there  is  a  long  vibratile  protoplasmic  filament 
(c),  by  means  of  which  the  cell  moves.  There  is  also  to  be  seen  near  this 
end  a  red  speck  (e)  which  is  probably  sensitive  to  light.  A  nucleus  can 
usually  be  seen  if  the  cell  is  first  killed  with  an  iodine  solution,  which 
often  will  render  the  flagellum  (c)  more  evident,  this  being  invisible  while 
the  cell  is  in  motion.  The  cells  multiply  by  division.  Previous  to  this 
the  flagellum  is  withdrawn,  and  a  firm  cell  wall  is  formed  about  the  cell 
(F?g.  9,  B).  The  contents  then  divide  into  two  or  more  parts,  which 
afterwards  escape  as  new  individuals. 


20 


BOTANY. 


Of  the  forms  that  are  united  in  colonies1  one  of  the  best 
known  is  Volvox  (Fig.  10).  This  plant  is  sometimes  found  in 
quiet  water,  where  it  floats  on  or  near  the  surface  as  a  dark 
green  ball,  just  large  enough  to  be  seen  with  the  naked  eye. 
They  may  be  kept  for  some  time  in  aquaria,  and  will  some- 
times multiply  rapidly,  but  are  very  susceptible  to  extremes 
of  temperature,  especially  of  heat. 

The  colony  (Fig.  10,  A)  is  a  hollow  sphere,  the  numerous  green  cells  of 
which  it  is  composed  forming  a  single  layer  on  the  outside.  By  killing 

with  iodine,  and  using  a  strong  lens, 
each  cell  is  seen  to  be  somewhat  pear- 
shaped  (Fig.  JB),  with  the  pointed  end 
out.  Attached  to  this  end  are  two 
vibratile  filaments  (cilia  or  flagella), 
and  the  united  movements  of  these 
cause  the  rolling  motion  of  the  whole 
colony.  Usually  a  number  of  young 
colonies  (Fig.  x)  are  found  within  the 
mother  colony.  These  arise  by  the 
repeated  bipartition  of  a  single  cell, 
and  escape  finally,  forming  independent 
colonies. 

Another  (sexual)  form  of  reproduction  occurs,  similar  to  that  found  in 
many  higher  plants ;  but  as  it  only  occurs  at  certain  seasons,  it  is  not 
likely  to  be  met  with  by  the  student. 

Other  forms  related  to  Volvox,  and  sometimes  met  with,  are 
Gonium,  in  which  there  are  sixteen  cells,  forming  a  flat  square ; 
Pandorina  and  Eudorina,  with  sixteen  cells,  forming  an  oval  or 
globular  colony  like  Volvox,  but  much  smaller.  In  all  of  these 
the  structure  of  the  cells  is  essentially  as  in  Volvox. 

1  The  term  "colony"  is,  perhaps,  inappropriate,  as  the  whole  mass  of 
cells  arises  from  a  single  one,  and  may  properly  be  looked  upon  as  an 
individual  plant. 


FIG.  10.  —  Volvox.  A,  mature  col- 
ony, containing  several  smaller 
ones  (x),  x  50.  B,  Two  cells 
showing  the  cilia,  x  300. 


CHAPTER  IV. 


SUB-KINGDOM  II. 


IN  the  second  sub-kingdom  of  plants  is  embraced  an  enor- 
mous assemblage  of  plants,  differing  widely  in  size  and  com- 
plexity, and  yet  showing  a  sufficiently  complete  gradation  from 
the  lowest  to  the  highest  as  to  make  it  impracticable  to  make 
more  than  one  sub-kingdom  to  include  them.  They  are  nearly 
all  aquatic  forms,  although  many  of  them  will  survive  long 
periods  of  drying,  such  forms  occurring  on  moist  earth,  rocks, 
or  the  trunks  of  trees,  but  only  growing  when  there  is  a 
plentiful  supply  of  water. 

All  of  them  possess  chlorophyll,  which,  however,  in  many 
forms,  is  hidden  by  the  presence  of  a  brown  or  red  pigment. 
They  are-  ordinarily  divided  into  three  classes  —  I.  The  Green 
Algae  (Chlorophycece)  ;  II.  Brown  Algae  (Phceophycece)  ;  III. 
Bed  Algae  (Rhodophycece)  . 

CLASS  I.  —  GREEN  ALG^;. 

The  green  algae  are  to  be  found  almost  everywhere  where 
there  is  moisture,  but  are  especially  abundant  in  sluggish  or 
stagnant  fresh  water,  being  much  less  common  in  salt  water. 
They  are  for  the  most  part  plants  of  simple  structure,  many 
being  unicellular,  and  very  few  of  them  plants  of  large  size. 

We  may  recognize  five  well-marked  orders  of  the  green  algae 
—  I.  Green  slimes  (Protococcacece)  ;  II.  Confervacece  ;  III.  Pond 
scums  (Conjugatce)  ;  IV.  Siphonece;  V.  Stone-worts  (Characece)  . 

1  Algae  (sing.  alga).  21 


22 


BOTANY. 


ORDER  I.  —  Protococcacece. 

The  members  of  this  order  are  minute  unicellular  plants, 
growing  either  in  water  or  on  the  damp  surfaces  of  stones,  tree 
trunks,  etc.  The  plants  sometimes  grow  isolated,  but  usually 
the  cells  are  united  more  or  less  regularly  into  colonies. 

A  common  representative  of  the  order  is  the  common  green 
slime,  Protococcus  (Fig.  11,  A,  C),  which  forms  a  dark  green 
slimy  coating  over  stones,  tree  trunks,  flower  pots,  etc.  Owing 
to  their  minute  size  the  structure  can  only  be  made  out  with 
the  microscope. 
A 


FIG.  \\.-ProtococcacesB.  A,  C,  Protococcus.  A,  single  cells.  B,  cells  divid- 
ing by  fission.  C,  successive  steps  in  the  process  of  internal  cell  division.  s  In 
C  iv,  the  young  cells  have  mostly  become  free.  D,  a  full-grown  colony  of 
Pediastrum.  E,  a  young  colony  still  surrounded  by  the  membrane  of  the 
mother  cell.  F,  Scenedesmus.  All,  x  300.  G,  small  portion  of  a  young 
colony  of  the  water  net  (Hydrodictyori) ,  x  150. 

Scraping  off  a  little  of  the  material  mentioned  into  a  drop  of  water  upon 
a  slide,  and  carefully  separating  it  with  needles,  a  cover  glass  may  be 
placed  over  the  preparation,  and  it  is  ready  for  examination.  When 
magnified,  the  green  film  is  found  to  be  composed  of  minute  globular  cells 
of  varying  size,  which  may  in  places  be  found  to  be  united  into  groups. 
With  a  higher  power,  each  cell  (Fig.  11,  A)  is  seen  to  have  a  distinct  cell 
wall,  within  which  is  colorless  protoplasm.  Careful  examination  shows 
that  the  chlorophyll  is  confined  to  several  roundish  bodies  that  are  not 
usually  in  immediate  contact  with  the  wall  of  the  cell.  These  green 
masses  are  called  chlorophyll  bodies  (chloroplasts).  Toward  the  centre 


ALG^E. 


23 


of  the  cell,  especially  if  it  has  first  been  treated  with  iodine,  the  nucleus 
may  be  found.  The  size  of  the  cells,  as  well  as  the  number  of  chloro- 
plasts,  varies  a  good  deal. 

With  a  little  hunting,  specimens  in  various  stages  of  division  may  be 
found.  The  division  takes  place  in  two  ways.  In  the  first  (Fig.  11,  .B), 
known  as  fission,  a  wall  is  formed  across  the  cell,  dividing  it  into  two  cells, 
which  may  separate  immediately  or  may  remain  united  until  they  have 
undergone  further  division.  In  this  case  the  original  cell  wall  remains  as 
part  of  the  wall  of  the  daughter  cells.  Fission  is  the  commonest  form  of 
cell  multiplication  throughout  the  vegetable  kingdom. 

The  second  form  of  cell  division  or  internal  cell  division  is  shown  at  C. 
Here  the  protoplasm  and  nucleus  repeatedly  divide  until  a  number  of 
small  cells  are  formed  within  the  old  one.  These  develop  cell  walls,  and 
escape  by  the  breaking  of  the  old  cell  wall,  which  is  left  behind,  and  takes 
no  part  in  the  process.  The  cells  thus  formed  are  sometimes  provided 
with  two  cilia,  and  are  capable  of  active  movement. 

Internal  cell  division,  as  we  shall  see,  is  found  in  most  plants,  but  only 
at  special  times. 

Closely  resembling  Protococcus,  and  answering  quite  as  well  for  study, 
are  numerous  aquatic  forms,  such  as  Chlorococcum  (Fig.  12).  These  are 
for  the  most  part  destitute  of  a  firm  cell  wall,  but  are  imbedded  in  masses 
of  gelatinous  substance  like  many  Cyanophycece.  The  chloroplasts  are 
smaller  and  less  distinct  than  in  Proto- 
coccus. The  cells  are  here  oval  rather 
than  round,  and  often  show  a  clear 
space  at  one  end. 

Owing  to  the  absence  of  a  definite 
membrane,  a  distinction  between  fis- 
sion and  internal  cell  division  can 
scarcely  be  made  here.  Often  the  cells 
escape  from  the  gelatinous  envelope, 
and  swim  actively  by  means  of  two 
cilia  at  the  colorless  end  (Fig.  12,  B}. 
In  this  stage  they  closely  resemble  the 
individuals  of  aVolvox  colony,  or  other 
green  Flagellata,  to  which  there  is  little 
doubt  that  they  are  related. 

There  are  a  number  of  curious  forms  common  hi  fresh  water  that  are 
probably  related  to  Protococcus,  but  differ  in  having  the  cells  united  hi 
colonies  of  definite  form.  Among  the  most  striking  are  the  different 
species  of  Pediastrum  (Fig.  11,  Z),  E),  often  met  with  in  company  with 


FIG.  12.  —  Chlorococcum,  a  plant 
related  to  Protococcus,  but  the 
naked  cells  are  surrounded  by  a 
colorless  gelatinous  envelope. 
A,  motionless  cells.  B,  a  cell 
that  has  escaped  from  its  enve- 
lope and  is  ciliated,  x  300. 


24  BOTANY. 

other  alga),  and  growing  readily  in  aquaria  when  once  established.  They 
are  of  very  elegant  shapes,  and  the  number  of  cells  some  multiple  of  four, 
usually  sixteen. 

The  cells  form  a  flat  disc,  the  outer  ones  being  generally  provided  with 
a  pair  of  spines. 

New  individuals  arise  by  internal  division  of  the  cells,  the  contents  of 
each  forming  as  many  parts  as  there  are  cells  in  the  whole  colony.  The 
young  cells  now  escape  through  a  cleft  in  the  wall  of  the  mother  cell,  but 
are  still  surrounded  by  a  delicate  membrane  (Fig.  11,  E).  Within  this 
membrane  the  young  cells  arrange  themselves  in  the  form  of  the  original 
colony,  and  grow  together,  forming  a  new  colony. 

A  much  larger  but  rarer  form  is  the  water  net  (Fig.  11,  6?), -in  which 
the  colony  has  the  form  of  a  hollow  net,  the  spaces  being  surrounded  by 
long  cylindrical  cells  placed  end  to  end.  Other  common  forms  belong  to 
the  genus  Scenedesmus  (Fig.  11,  F),  of  which  there  are  many  species. 

ORDER  II.  —  Confervacece. 

Under  this  head  are  included  a  number  of  forms  of  which 
the  simplest  ones  approach  closely,  especially  in  their  younger 
stages,  the  Protococcacece.  Indeed,  some  of  the  so-called  Proto- 
coccacece  are  known  to  be  only  the  early  stages  of  these  plants. 

A  common  member  of  this  order  is  Cladophora,  a  coarse- 
branching  alga,  growing  commonly  in  running  water,  where  it 
forms  tufts,  sometimes  a  metre  or  more  in  length.  By  floating 
out  a  little  of  it  in  a  saucer,  it  is  easy  to  see  that  it  is  made  up 
of  branching  filaments. 

The  microscope  shows  (Fig.  13,  A)  that  these  filaments  are  rows  of 
cylindrical  cells  with  thick  walls  showing  evident  stratification.  At 
intervals  branches  are  given  off,  which  may  in  turn  branch,  giving  rise  to 
a  complicated  branching  system.  These  branches  begin  as  little  pro- 
tuberances of  the  cell  wall  at  the  top  of  the  cell.  They  increase  rapidly 
in  length,  and  becoming  slightly  contracted  at  the  base,  a  wall  is  formed 
across  at  this  point,  shutting  it  off  from  the  mother  cell. 

The  protoplasm  lines  the  wall  of  the  cell,  and  extends  in  the  form  of 
thin  plates  across  the  cavity  of  the  cell,  dividing  it  up  into  a  number  of 
irregular  chambers.  Imbedded  in  the  protoplasm  are  numerous  flattened 
chloroplasts,  which  are  so  close  together  as  to  make  the  protoplasm  appear 
almost  uniformly  green.  Within  the  chloroplasts  are  globular,  glistening 


bodies,  called  "  pyrenoids. "  The  cell  has  several  nuclei,  but  they  are 
scarcely  evident  in  the  living  cell.  By  placing  the  cells  for  a  few  hours  in 
a  one  per  cent  watery  solution  of  chromic  acid,  then  washing  thoroughly 


FIG.  13.  —  Cladophora.  A,  a  fragment  of  a  plant,  x  50.  B,  a  single  cell  treated 
with  chromic  acid,  and  stained  with  alum  cochineal,  n,  nucleus,  py.  pyre- 
noid,  x  150.  C,  three  stages  in  the  division  of  a  cell,  i,  1.45  p.m.;  n,  2.55 
p.m. ;  in,  4.15  p.m.,  x  150.  D,  a  zoospore  x  350. 

and  staining  with  borax  carmine,  the  nuclei  will  be  made  very  evident 
(Fig.  13,  B).  Such  preparations  may  be  kept  permanently  in  dilute 
glycerine. 

If  a  mass  of  actively  growing  filaments  is  examined,  some  of  the  cells 
will  probably  be  found  in  process  of  fission.  The  process  is  very  simple, 
and  may  be  easily  followed  (Fig.  13,  C).  A  ridge  .of  cellulose  is  formed 
around  the  cell  wall,  projecting  inward,  and  pushing  in  the  protoplasm  as 
it  grows.  The  process  is  continued  until  the  ring  closes  in  the  middle, 
cutting  the  protoplasmic  body  completely  in  two,  and  forms  a  firm 
membrane  across  the  middle  of  the  cell.  The  protoplasm  at  this  stage 
(C  in.)  is  somewhat  contracted,  but  soon  becomes  closely  applied  to  the 
new  wall.  The  whole  process  lasts,  at  ordinary  temperatures  (20°-25°  C.), 
from  three  to  four  hours. 

At  certain  times,  but  unfortunately  not  often  to  be  met  with,  the  con- 
tents of  some  of  the  cells  form,  by  internal  division,  a  large  number  of 
small,  naked  cells  (zoospores)  (Fig.  13,  D),  which  escape  and  swim  about 
actively  for  a  time,  and  afterwards  become  invested  with  a  cell  wall,  and 
grow  into  a  new  filament.  These  cells  are  called  zoospores,  from  their 
animal-like  movements.  They  are  provided  with  two  cilia,  closely  re- 
sembling the  motile  cells  of  the  Protococcacece  and  Volvocineoc. 


26 


BOTANY. 


There  are  very  many  examples  of  these  simple  Confervacece, 
some  like  Conferva   being   simple   rows  of   cells,    others  like 

Stigeodonium  (Fig. 
14,  A),  Chcetophora 
and  Drapamaldia 
(Fig.  14,^,0),  very 
much  branched.  The 
two  latter  forms  are 
surrounded  by  mass- 
es of  transparent 
jelly,  which  some- 
times reach  a  length 
of  several  centime- 
tres. 


Drapamaldia,  x  50.    C,  a  piece  of  Drapamaldia, 
x  2.    D,  part  of  a  filament  of  Conferva,  x  300. 


FIG.  14.  —  ConfervacesB.     A,   Stigeodonium. 

Among    the    ma- 
rine  forms    related 

to  these  may  be  mentioned  the  sea  lettuce  ( Ulva),  shown  in 

Figure  15.     The  thin,  bright-green,  leaf-like  fronds  of  this  plant 

are  familiar  to  every  seaside  student. 

Somewhat  higher  than  Cladophora, 
and  its  allies,  especially  in  the  differ- 
entiation of  the  reproductive  parts,  are 
the  various  species  of  (Edogonium  and 
its  relatives.  There  are  numerous 
species  of  (Edogonium  not  uncommon 
in  stagnant  water  growing  in  company 
with  other  algae,  but  seldom  forming 
masses  by  themselves  of  sufficient  size 
to  be  recognizable  to  the  naked  eye. 

The  plant  is  in  structure  much  like  Clado- 
phora, except  that  it  is  unbranched,  and  the 
cells  have  but  a  single  nucleus  (Fig.  16,  E). 
Even  when  not  fruiting  the  filaments  may  usually  be  recognized  by  pecu- 
liar cap-shaped  structures  at  the  top  of  some  of  the  cells.  These  arise  as 
the  result  of  certain  peculiarities  in  the  process  of  cell  division,  which  are 
too  complicated  to  be  explained  here. 


FIG.  15.  —  A  plant  of  sea 
lettuce  (Ulva).  One-half 
natural  size. 


27 


There  are  two  forms  of  reproduction,  non-sexual  and  sexual.  In  the 
first  the  contents  of  certain  cells  escape  in  the  form  of  large  zoospores 
(Fig.  16,  C),  of  oval  form,  having  the  smaller  end  colorless  and  surrounded 
by  a  crown  of  cilia.  After  a  short  period  of  active  motion,  the  zoospore 
comes  to  rest,  secretes  a  cell  wall  about  itself,  and  the  transparent  end 
becomes  flattened  out 
into  a  disc  (£",  tZ),  by 
which  it  fastens  itself 
to  some  object  in  the 
water.  The  upper  part 
now  rapidly  elongates, 
and  dividing  repeat- 
edly by  cross  walls, 
develops  into  a  fila- 
ment like  the  original 
one.  In  many  species 
special  zoospores  are 
formed,  smaller  than 
the  ordinary  ones,  that 
attach  themselves  to 
the  filaments  bearing 
the  female  reproduc- 
tive organ  (oogonium), 
and  grow  into  small 
plants  bearing  the 
male  organ  (antherid- 
ium),  (Fig.  16,  B}. 

The  sexual  repro- 
duction takes  place  as 
follows :  Certain  cells 
of  a  filament  become 
distinguished  by  their 
denser  contents  and 
by  an  increase  in  size, 
becoming  oval  or  nearly  globular  in  form  (Fig.  16,  A,  B).  When  fully 
grown,  the  contents  contract  and  form  a  naked  cell,  which  sometimes 
shows  a  clear  area  at  one  point  on  the  surface.  This  globular  mass  of 
protoplasm  is  the  egg  cell,  or  female  cell,  and  the  cell  containing  it  is 
called  the  "  oogonium."  When  the  egg  cell  is  ripe,  the  oogonium  opens 
by  means  of  a  little  pore  at  one  side  (Fig.  16,  A). 

In  other  cells,  either  of  the  same  filament  or  else  of  the  small  male 


an. 


FIG.  16.  —  A,  portion  of  a  filament  of  (Edogonium, 
with  two  oogonia  (o</.).  The  lower  one  shows  the 
opening.  B,  a  similar  filament,  to  which  is  at- 
tached a  small  male  plant  with  an  antheridium 
(an.).  C,  a  zoospore  of  (Edoc/onium.  D,  a  similar 
spore  germinating.  E,  base  of  a  filament  showing 
the  disc  (d)  by  which  it  is  attached.  F,  another 
species  of  CEdoyonium  with  a  ripe  spore  (sp.)  G, 
part  of  a  plant  of  Bulbochsete.  C,  D,  x  300;  the 
others  x  150. 


28  BOTANY. 

plants  already  mentioned,  small  motile  cells,  called  spermatozoids,  are 
formed.  These  are  much  smaller  than  the  egg  cell,  and  resemble  the 
zoospores  in  form,  but  are  much  smaller,  and  without  chlorophyll.  When 
ripe  they  are  discharged  from  the  cells  in  which  they  were  formed,  and 
enter  the  oogonium.  By  careful  observation  the  student  may  possibly  be 
able  to  follow  the  spermatozoid  into  the  oogonium,  where  it  enters  the  egg 
cell  at  the  clear  spot  on  its  surface.  As  a  result  of  the  entrance  of  the 
spermatozoid  (fertilization),  the  egg  cell  becomes  surrounded  by  a  thick 
brown  wall,  and  becomes  a  resting  spore.  The  spore  loses  its  green  color, 
and  the  wall  becomes  dark  colored  and  differentiated  into  several  layers, 
the  outer  one  often  provided  with  spines  (Fig.  16,  F).  As  these  spores  do 
not  germinate  for  a  long  time,  the  process  is  only  known  in  a  compara- 
tively small  number  of  species,  and  can  hardly  be  followed  by  the  ordi- 
nary student. 

Much  like  (Edogonium,  but  differing  in  being  branched,  is 
the  genus  Bulbochcete,  characterized  also  by  hairs  swollen  at 
the  base,  and  prolonged  into  a  delicate  filament  (Fig.  16,  G). 

The  highest  members  of  the  Confervacece  are  those  of  the 


FIG.  17.  —  A,  plant  of  Coleochsete,  x  50.    B,  a  few  cells  from 
the  margin,  with  one  of  the  hairs. 

genus  Coleochcele  (Fig.  17),  of  which  there  are  several  species 
found  in  the  United  States.  These  show  some  striking  resem- 
blances to  the  red  seaweeds,  and  possibly  form  a  transition 
from  the  green  algae  to  the  red.  The  commonest  species  form 


.  29 

bright-green  discs,  adhering  firmly  to  the  stems  and  floating 
leaves  of  water  lilies  and  other  aquatics.  In  aquaria  they 
sometimes  attach  themselves  in  large  numbers  to  the  glass 
sides  of  the  vessel. 

Growing  from  the  upper  surface  are  numerous  hairs,  consisting  of  a 
short,  sheath-like  base,  including  a  very  long  and  delicate  filament  (Fig. 
17,  J9).  In  their  methods  of  reproduction  they  resemble  CEdogonium, 
but  the  reproductive  organs  are  more  specialized. 


CHAPTER    V. 

GREEN  ALGJK  —  Continued. 
ORDER  III. — POND  SCUMS  (Conjugates). 

THE  Conjugatce,  while  in  some  respects  approaching  the 
Confervacece  in  structure,  yet  differ  from  them  to  such  an 
extent  in  some  respects  that  their  close  relationship  is  doubt- 
ful. They  are  very  common  and  familiar  plants,  some  of  them 
forming  great  floating  masses  upon  the  surface  of  every  stag- 
nant pond  and  ditch,  being  commonly  known  as  "  pond  scum." 
The  commonest  of  these  pond  scums  belong  to  the  genus 
Spirogyra,  and  one  of  these  will  illustrate  the  characteristics  of 
the  order.  When  in  active  growth  these  masses  are  of  a  vivid 
green,  and  owing  to  the  presence  of  a  gelatinous  coating  feel 
slimy,  slipping  through  the  hands  when  one  attempts  to  lift 
them  from,  the  water.  Spread  out  in  water,  the  masses  are 
seen  to  be  composed  of  slender  threads,  often  many  centi- 
metres in  length,  and  showing  no  sign  of  branching. 

For  microscopical  examination  the  larger  species  are  preferable.  When 
one  of  these  is  magnified  (Fig.  18,  A,  (7),  the  unbranched  filament  is 
shown  to  be  made  up  of  perfectly  cylindrical  cells,  with  rather  delicate 
walls.  The  protoplasm  is  confined  to  a  thin  layer  lining  the  walls,  except 
for  numerous  fine  filaments  that  radiate  from  the  centrally  placed 
nucleus  (n),  which  thus  appears  suspended  in  the  middle  of  the  cell.  The 
nucleus  is  large  and  distinct  in  the  larger  species,  and  has  a  noticeably 
large  and  conspicuous  nucleolus.  The  most  noticeable  thing  about  the 
cell  is  the  green  spiral  bands  running  around  it.  These  are  the  chloro- 
plasts,  which  in  all  the  Conjugatce  are  of  very  peculiar  forms.  The  num- 
ber of  these  bands  varies  much  in  different  species  of  Spirogyra,  but  is 
commonly  two  or  three.  These  chloroplasts,  like  those  of  other  plants, 
are  not  noticeably  different  in  structure  from  the  ordinary  protoplasm,  as 


GEEEN  ALGJE. 


31 


is  shown  by  extracting  the  chlorophyll,  which  may  be  done  by  placing  the 
plants  in  alcohol  for  a  short  time.  This  extracts  the  chlorophyll,  but  a 
microscopic  examination  of  the  decolored  cells  shows  that  the  bands 
remain  unchanged,  except  for  the  absence  of  color.  These  bands  are 
flattened,  with  irregularly  scalloped  margins,  and  at  intervals  have 
rounded  bodies  (pyrenoids)  imbedded  in  them  (Fig.  18,  0,  py.).  The 
pyrenoids,  especially  when  the  plant  has  been  exposed  to  the  light  for 
some  time,  are  surrounded  by  a  circle  of  small  granules,  which  become 


FIG.  18.  —  A ,  a  filament  of  a  common  pond  scum  (Spirogyra)  separating  into 
two  parts.  B,  a  cell  undergoing  division.  The  cell  is  seen  in  optical  section, 
and  the  chlorophyll  bands  are  omitted,  n,  n',  the  two  nuclei.  C,  a  complete 
cell,  n,  nucleus,  py.  pyrenoid.  D,  E,  successive  stages  in  the  process  of 
conjugation.  G,  a  ripe  spore.  H,  a  form  in  which  conjugation  takes  place 
between  the  cells  of  the  same  filament.  All  x  150. 

bluish  when  iodine  is  applied,  showing  them  to  be  starch.  (To  show  the 
effect  of  iodine  on  starch  on  a  large  scale,  mix  a  little  flour,  which  is  nearly 
all  starch,  with  water,  and  add  a  little  iodine.  The  starch  will  immediately 
become  colored  blue,  varying  in  intensity  with  the  amount  of  iodine.)  The 
cells  divide  much  as  in  Cladophora,  but  the  nucleus  here  takes  part  in  the 
process.  The  division  naturally  occurs  only  at  night,  but  by  reducing  the 
temperature  at  night  to  near  the  freezing  point  (4°  C.,  or  a  little  lower),  the 
process  may  be  checked.  The  experiment  is  most  conveniently  made  when 


32  BOTANY. 

the  temperature  out  of  doors  approaches  the  freezing  point.  Then  it  is 
only  necessary  to  keep  the  plants  in  a  warm  room  until  about  10  P.M.,  when 
they  may  be  put  out  of  doors  for  the  night.  On  bringing  them  in  in  the 
morning,  the  division  will  begin  almost  at  once,  and  may  be  easily 
studied.  The  nucleus  divides  into  two  parts,  which  remain  for  a  time 
connected  by  delicate  threads  (Fig.  18,  J5),  that  finally  disappear.  At 
first  no  nucleoli  are  present  in  the  daughter  nuclei,  but  they  appear  before 
the  division  is  complete. 

New  filaments  are  formed  by  the  breaking  up  of  the  old  ones,  this 
sometimes  being  very  rapid.  As  the  cells  break  apart,  the  free  ends  bulge 
strongly,  showing  the  pressure  exerted  upon  the  cell  wall  by  the  contents 
(Fig.  18,  A). 

Spores  like  those  of  (Edogonium  are  formed,  but  the  process 
is  somewhat  different.  It  occurs  in  most  species  late  in  the 
spring,  but  may  sometimes  be  met  with  at  other  times.  The 
masses  of  fruiting  plants  usually  appear  brownish  colored.  If 
spores  have  been  formed  they  can,  in  the  larger  species  at 
least,  *be  seen  with  a  hand  lens,  appearing  as  rows  of  dark- 
colored  specks. 

Two  filaments  lying  side  by  side  send  out  protuberances  of  the  cell 
wall  that  grow  toward  each  other  until  they  touch  (Fig.  18,  D).  At  the 
point  of  contact,  the  wall  is  absorbed,  forming  a  continuous  channel 
from  one  cell  to  the  other.  This  process  usually  takes  place  in  all  the 
cells  of  the  two  filaments,  so  that  the  two  filaments,  connected  by  tubes  at 
regular  intervals,  have  the  form  of  a  ladder. 

In  some  species  adjoining  cells  of  the  same  filament  become  connected, 
the  tubes  being  formed  at  the  end  of  the  cells  (Fig.  18,  #),  and  the  cell  in 
which  the  spore  is  formed  enlarges. 

Soon  after  the  channel  is  completed,  the  contents  of  one  cell  flow  slowly 
through  it  into  the  neighboring  cell,  and  the  protoplasm  of  the  two  fuses 
into  one  mass.  (The  union  of  the  nuclei  has  also  been  observed.)  The 
young  spore  thus  formed  contracts  somewhat,  becoming  oval  in  form,  and 
soon  secretes  a  thick  wall,  colorless  at  first,  but  afterwards  becoming 
brown  and  more  or  less  opaque.  The  chlorophyll  bands,  although  much 
crowded,  are  at  first  distinguishable,  but  later  lose  the  chlorophyll,  and 
become  unrecognizable.  Like  the  resting  spores  of  (Edogonium  these 
require  a  long  period  of  rest  before  germinating. 

There  are  various  genera  of  the  pond  scums,  differing  in  the 
form  of  the  chloroplasts  and  also  in  the  position  of  the  spores. 


GEEEN  ALG^E. 


33 


Of  these  may  be  mentioned  Zygnema  (Fig.  19,  A),  with  two 
star-shaped  chloroplasts  in  each  cell,  and  Mesocarpus  (Fig.  19, 
B,  D),  in  which  the  single  chloroplast  has  the  form  of  a  thin 
median  plate.  (_B  shows  the 
appearance  from  in  front,  C 
from  the  side,  showing  the 
thickness  of  the  plate.)  Me- 
socarpus and  the  allied  gen- 
era have  the  spore  formed 
between  the  filaments,  the 
contents  of  both  the  uniting 
cells  leaving  them. 

Evidently  related  to  the 
pond  scums,  but  differing  in 
being  for  the  most  part 
strictly  unicellular,  are  the 
desmids  (Fig.  20).  They  are  confined  to  fresh  water,  and 
seldom  occur  in  masses  of  sufficient  size  to  be  seen  with  the 
naked  eye,  usually  being 
found  associated  with 
pond  scums  or  other  fila- 
mentous forms.  Many  of 
the  most  beautiful  forms 
may  be  obtained  by  ex- 
amining the  matter  ad- 
hering to  the  leaves  and 
stems  of  many  floating 
water  plants,  especially 


FIG.  19.  —  Forms  of  Zyynemacese.  A, 
Zygnema.  B,  C,  1),  Mesocarpus. 
All  x  150. 


the  bladder  weed  (  Uiricu- 
laria)  and  other  fine- 
leaved  aquatics. 


FIG.  20.  —  Forms  of  Desmids.  A,  B,  Clos- 
teriwn.  C,  D,  D',  Cosmarium.  D,  and 
D'  show  the  process  of  division.  E,  F, 
Staurastrum ;  E  seen  from  the  side,  F 
from  the  end. 


The  desmids  include  the  most  beautiful  examples  of  unicellular  plants 
to  be  met  with,  the  cells  having  extremely  elegant  outlines.  The  cell 
shows  a  division  into  two  parts,  and  is  often  constricted  in  the  middle, 


34  BOTANY. 

each  division  having  a  single  large  chloroplast  of  peculiar  form.     The 
central  part  of  the  cell  in  which  the  nucleus  lies  is  colorless. 

Among  the  commonest  forms,  often  growing  with  Spirogyra,  are 
various  species  of  Closterium  (Fig.  20,  A,  B),  recognizable  at  once  by 
their  crescent  shape.  The  cell  appears  bright  green,  except  at  the  ends 
and  in  the  middle.  The  large  chloroplast  in  each  half  is  composed  of  six 
longitudinal  plates,  united  at  the  axis  of  the  cell.  Several  large  pyrenoids 
are  always  found,  often  forming  a  regular  line  through  the  central  axis. 
At  each  end  of  the  cell  is  a  vacuole  containing  small  granules  that  show 
an  active  dancing  movement. 

The  desmids  often  have  the  power  of  movement,  swimming 
or  creeping  slowly  over  the  slide  as  we  examine  them,  but  the 
mechanism  of  these  movements  is  still  doubtful. 

In  their  reproduction  they  closely  resemble  the  pond  scums. 


ORDER  IV.  —  Siphonece. 

The  SiphoneoR  are  algae  occurring  both  in  fresh  and  salt 
water,  and  are  distinguished  from  other  algae  by  having  the 
form  of  a  tube,  undivided  by  partition  walls,  except  when  re- 
production occurs.  The  only  common  representatives  of  the 
order  in  fresh  water  are  those  belonging  to  the  genus  Vauclieria, 
but  these  are  to  be  had  almost  everywhere.  They  usually 
occur  in  shallow  ditches  and  ponds,  growing  on  the  bottom,  or 
not  infrequently  becoming  free,  and  floating  where  the  water 
is  deeper.  They  form  large,  dark  green,  felted  masses,  and  are 
sometimes  known  as  "  green  felts."  Some  species  grow  also  on 
the  wet  ground  about  springs.  An  examination  of  one  of  the 
masses  shows  it  to  be  made  up  of  closely  matted,  hair-like 
threads,  each  of  which  is  an  individual  plant. 

In  transferring  the  plants  to  the  slide  for  microscopic  examination,  they 
must  be  handled  very  carefully,  as  they  are  very  easily  injured.  Each 
thread  is  a  long  tube,  branching  sometimes,  but  not  divided  into  cells 
as  in  Spirogyra  or  Cladophora.  If  we  follow  it  to  the  tip,  the  contents 
here  will  be  found  to  be  denser,  this  being  the  growing  point.  By  careful 


GEEEN  ALG^E. 


35 


focusing  it  is  easy  to  show  that  the  protoplasm  is  confined  to  a  thin  layer 
lining  the  wall,  the  central  cavity  of  the  tube  being  filled  with  cell  sap.  In 
the  protoplasm  are  numerous  elongated  chloroplasts  (cL),  and  a  larger  or 
smaller  number  of  small,  shining,  globular  bodies  (ol.).  These  latter  are 
drops  of  oil,  and,  when  the  filaments  are  injured,  sometimes  run  together, 
and  form  drops  of  large  size.  No  nucleus  can  be  seen  in  the  living  plant, 
but  by  treatment  with  chromic  acid  and  staining,  numerous  very  small 
nuclei  may  be  demonstrated. 

When  the  filaments  are  growing  upon  the  ground,  or  at  the  bottom  of 


FIG.  21. —  A,  C,  successive  stages  in  the  development  of  the  sexual  organs  of  a 
green  felt  (Vaucheria).  ori.antheridium.  or/, oogonium.  D, a  ripe oogonium. 
E,  the  same  after  it  has  opened,  o,  the  egg  cell.  F,  a  ripe  spore.  G,  a 
species  in  which  the  sexual  organs  are  borne  separately  on  the  main  filament. 
A,  F,  x  150.  G,  x  50.  cl.  chloroplasts.  ol.  oil. 


shallow  water,  the  lower  end  is  colorless,  and  forms  a  more  or  less  branch- 
ing root-like  structure,  fastening  it  to  the  earth.  These  rootlets,  like  the 
rest  of  the  filament,  are  undivided  by  walls. 

One  of  the  commonest  and  at  the  same  time  most  characteristic  species 
is  Vaucheria  racemosa  (Fig.  21,  A,  F).  The  plant  multiplies  non-sexually 
by  branches  pinched  off  by  a  constriction  at  the  point  where  they  join 
the  main  filament,  or  by  the  filament  itself  becoming  constricted  and  sep- 
arating into  several  parts,  each  one  constituting  a  new  individual. 


36 


BOTANY. 


The  sexual  organs  are  formed  on  special  branches,  and  their  arrange- 
ment is  such  as  to  make  the  species  instantly  recognizable. 

The  first  sign  of  their  development  is  the  formation  of  a  short  branch 
(Fig.  21,  A)  growing  out  at  right  angles  to  the  main  filament.  This  branch 
becomes  club-shaped,  and  the  end  somewhat  pointed  and  more  slender, 
and  curves  over.  This  slender,  curved  portion  is  almost  colorless,  and  is 
soon  shut  off  from  the  rest  of  the  branch.  It  is  called  an  "  antheridium," 
and  within  are  produced,  by  internal  division,  numerous  excessively  small 
spermatozoids. 

As  the  branch  grows,  its  contents  become  very  dense,  the  oil  drops 
especially  increasing  in  number  and  size.  About  the  time  that  the 
antheridium  becomes  shut  off,  a  circle  of  buds  appears  about  its  base 
(Fig.  21,  B,  og.).  These  are  the  young  oogonia,  which  rapidly  increase 
in  size,  assuming  an  oval  form,  and  become  separated  by  walls  from  the 
main  branch  (O).  Unlike  the  antheridium,  the  oogonia  contain  a  great 
deal  of  chlorophyll,  appearing  deep  green. 

When  ripe,  the  antheridium  opens  at  the  end  and  discharges  the  sper- 
matozoids, which  are,  however,  so  very  small  as  scarcely  to  be  visible 

except  with  the  strongest  lenses.  They 
are  little  oval  bodies  with  two  cilia,  which 
may  sometimes  be  rendered  visible  by 
staining  with  iodine. 

The  oogonia,  which  at  first  are  uni- 
formly colored,  just  before  maturity  show 
a  colorless  space  at  the  top,  from  which 
the  chloroplasts  and  oil  drops  have  dis- 
appeared (Z>),  and  at  the  same  time  this 
portion  pushes  out  in  the  form  of  a  short 
beak.  Soon  after  the  wall  is  absorbed  at 
this  point,  and  a  portion  of  the  contents  is 
forced  out,  leaving  an  opening,  and  at  the 
same  time  the  remaining  contents  con- 
tract to  form  a  round  mass,  the  germ  or 
egg  cell  (Fig.  21,  E,  o).  Almost  as  soon 
as  the  oogonium  opens,  the  spermatozoids 

collect  about  it  and  enter  ;  but,  on  account  of  their  minuteness,  it  is  almost 
impossible  to  follow  them  into  the  egg  cell,  or  to  determine  whether  several 
or  only  one  enter.  The  fertilized  egg  cell  becomes  almost  at  once  sur- 
rounded by  a  wall,  which  rapidly  thickens,  and  forms  a  resting  spore.  As 
the  spore  ripens,  it  loses  its  green  color,  becoming  colorless,  with  a  few 
reddish  brown  specks  scattered  through  it  (F). 


IV 


FIG.  22.  —  A,  non-sexual  repro- 
duction in  Vaucheria  sessilis. 
B,  non-sexual  spore  of  V. 
(/eminata,  x  50. 


GEEEN  ALG^.  37 


In  some  species  the  sexual  organs  are  borne  directly  on  the  filament 
(Fig.  21,  0). 

Large  zoospores  are  formed  in  some  of  the  green  felts  (Fig.  22,  A),  and 
are  produced  singly  in  the  ends  of  branches  that  become  swollen,  dark 
green,  and  filled  with  very  dense  protoplasm.  This  end  becomes  separated 
by  a  wall  from  the  rest  of  the  branch,  the  end  opens,  and  the  contents 
escape  as  a  very  large  zoospore,  covered  with  numerous  short  cilia  (A  n). 
After  a  short  period  of  activity,  this  loses  its  cilia,  develops  a  wall,  and 
begins  to  grow  (in,  iv).  Other  species  (B)  produce  similar  spores,  which, 
however,  are  not  motile,  and  remain  within  the  mother  cell  until  they  are 
set  free  by  the  decay  of  its  wall. 


ORDER  V.  —  Characece. 

The  Characece,  or  stone-worts,  as  some  of  them  are  called,  are 
so  very  different  from  the  other  green  algae  that  it  is  highly 
probable  that  they  should  be  separated  from  them. 

The  type  of  the  order  is  the  genus  Chara  (Fig.  23),  called 
stone-worts  from  the  coating  of  carbonate  of  lime  found  in 
most  of  them,  giving  them  a  harsh,  stony  texture.  Several 
species  are  common  growing  upon  the  bottom  of  ponds  and 
slow  streams,  and  range  in  size  from  a  few  centimetres  to  a 
metre  or  more  in  height. 

The  plant  (Fig.  23,  A)  consists  of  a . central  jointed  axis 
with  circles  of  leaves  at  each  joint  or  node.  The  distance 
between  the  nodes  (internodes)  may  in  the  larger  species 
reach  a  length  of  several  centimetres.  The  leaves  are  slen- 
der, cylindrical  structures,  and  like  the  stem  divided  into  nodes 
and  internodes,  and  have  at  the  nodes  delicate  leaflets. 

At  each  joint  of  the  leaf,  in  fruiting  specimens,  attached  to 
the  inner  side,  are  borne  two  small,  roundish  bodies,  in  the 
commoner  species  of  a  reddish  color  (Fig.  23,  A,  r).  The 
lower  of  the  two  is  globular,  and  bright  scarlet  in  color ;  the 
other,  more  oval  and  duller. 

Examined  with  a  lens  the  main  axis  presents  a  striated 
appearance.  The  whole  plant  is  harsh  to  the  touch  and  brittle, 


38 


BOTANY. 


owing  to  the  limy  coating.     It  is  fastened  to  the  ground  by 
fine,  colorless  hairs,  or  rootlets. 

By  making  a  series  of  longitudinal  sections  with  a  sharp  razor  through 
the  top  of  the  plant,  and  magnifying  sufficiently,  it  is  found  to  end  in 
a  single,  nearly  hemispherical  cell  (Fig.  23,  J?,  S).  This  from  its  posi- 


FIG.  23.  —  A,  plant  of  a  stone- wort  (Chara),  one-half  natural  size,  r,  repro- 
ductive organs.  B,  longitudinal  section  through  the  apex.  S,  apical  cell. 
x,  nodes,  y,  internodes.  C,  a  young  leaf.  D,  cross  section  of  an  internode. 
E,  of  a  node  of  a  somewhat  older  leaf.  F,  G,  young  sexual  organs  seen  in 
optical  section,  o,  oogonium.  An.  antheridium.  H,  superficial  view.  G,  I, 
group  of  filaments  containing  spermatozoids.  J,  a  small  portion  of  one  of 
these  more  magnified,  showing  a  spermatozoid  in  each  cell.  K,  free  sperma- 
tozoids. L,  a  piece  of  a  leaf  with  ripe  oogonium  (o),  and  antheridium  (An.). 
B,  H,  x  150.  J,  K,  x  300.  I,  x  50.  L,  x  25. 

tion  is  called  the  "apical  cell,"  and  from  it  are  derived  all  the  tissues  of 
the  plant.  Segments  are  cut  off  from  its  base,  and  these  divide  again  into 
two  by  a  wall  parallel  to  the  first.  Of  the  two  cells  thus  formed  one 
undergoes  no  further  division  and  forms  the  central  cell  of  an  inter- 
node  (y)  ;  the  other  divides  repeatedly,  forming  a  node  or  joint  (x). 
As  the  arrangement  of  these  cells  is  essentially  the  same  In  the 


GREEN  ALG^E.  39 

leaves  and  stem,  we  will  examine  it  in  the  former,  as  by  cutting  several 
cross- sections  of  the  whole  bunch  of  young  leaves  near  the  top  of  the 
plant,  we  shall  pretty  certainly  get  some  sections  through  a  joint.  The 
arrangement  is  shown  in  Figure  23,  E. 

As  the  stem  grows,  a  covering  is  formed  over  the  large  internodal 
cell  (y)  by  the  growth  of  cells  from  the  nodes.  These  grow  both  from 
above  and  below,  meeting  in  the  middle  of  the  internode  and  completely 
hiding  the  long  axial  cell.  A  section  across  the  internode  shows  the 
large  axial  cell  (y)  surrounded  by  the  regularly  arranged  cells  of  the 
covering  or  cortex  (Fig.  23,  D). 

All  the  cells  contain  a  layer  of  protoplasm  next  the  wall  with  numerous 
oval  chloroplasts.  If  the  cells  are  uninjured,  they  often  show  a  very 
marked  movement  of  the  protoplasm.  These  movements  are  best  seen, 
however,  in  forms  like  Nitella,  where  the  long  internodal  cells  are  not 
covered  with  a  cortex.  In  Chara  they  are  most  evident  in  the  root  hairs 
that  fasten  the  plant  to  the  ground. 

The  growth  of  the  leaves  is  almost  identical  with  that  of  the  stem, 
but  the  apical  growth  is  limited,  and  the  apical  cell  becomes  finally  very 
long  and  pointed  (Fig.  23,  (7).  In  some  species  the  chloroplasts  are 
reddish  in  the  young  cells,  assuming  their  green  color  as  the  cells  ap- 
proach maturity. 

The  plant  multiplies  non-sexually  by  means  of  special 
branches  that  may  become  detached,  but  there  are  no  non- 
sexual  spores  formed. 

The  sexual  organs  have  already  been  noticed  arising  in  pairs  at  the 
joints  of  the  leaves.  The  oogonium  is  formed  a*bove,  the  antheridium 
below. 

The  young  oogonium  (F,  0)  consists  of  a  central  cell,  below  which 
is  a  smaller  one  surrounded  by  a  circle  of  five  others,  which  do  not  at 
first  project  above  the  central  cell,  but  later  completely  envelop  it  (G). 
Each  of  these  five  cells  early  becomes  divided  into  an  upper  and  a  lower 
one,  the  latter  becoming  twisted  as  it  elongates,  and  the  central  cell  later 
has  a  small  cell  cut  off  from  its  base  by  an  oblique  wall.  The  central 
cell  forms  the  egg  cell,  which  in  the  ripe  oogonium  (L,  0)  is  surrounded 
by  five,  spirally  twisted  cells,  and  crowned  by  a  circle  of  five  smaller  ones, 
which  become  of  a  yellowish  color  when  full  grown.  They  separate  at 
the  time  of  fertilization  to  allow  the  spermatozoids  to  enter  the  oogonium. 

The  antheridium  consists  at  first  of  a  basal  cell  and  a  terminal  one. 
The  latter,  which  is  nearly  globular,  divides  into  eight  nearly  similar  cells  by 


40  BOTANY, 

walls  passing  through  the  centre.  In  each  of  these  eight  cells  two  walls  are 
next  formed  parallel  to  the  outer  surface,  so  that  the  antheridium  (apart 
from  the  basal  cell)  contains  twenty- four  cells  arranged  in  three  concentric 
series  (G,  an.).  These  cells,  especially  the  outer  ones,  develop  a  great 
amount  of  a  red  pigment,  giving  the  antheridium  its  characteristic  color. 

The  diameter  of  the  antheridium  now  increases  rapidly,  and  the  central 
cells  separate,  leaving  a  large  space  within.  Of  the  inner  cells,  the  second 
series,  while  not  increasing  in  diameter,  elongate,  assuming  an  oblong 
form,  and  from  the  innermost  are  developed  long  filaments  (7,  J)  com- 
posed of  a  single  row  of  cells,  in  each  of  which  is  formed  a  spermatozoid. 

The  eight  outer  cells  are  nearly  triangular  in  outline,  fitting  together  by 
deeply  indented  margins,  and  having  the  oblong  cells  with  the  attached 
filaments  upon  their  inner  faces. 

If  a  ripe  antheridium  is  crushed  in  a  drop  of  water,  after  lying  a  few 
minutes  the  spermatozoids  will  escape  through  small  openings  in  the  side 
of  the  cells.  They  are  much  larger  than  any  we  have  met  with.  Each 
is  a  colorless,  spiral  thread  with  about  three  coils,  one  end  being  some- 
what dilated  with  a  few  granules ;  the  other  more  pointed,  and  bearing 
two  extremely  long  and  delicate  cilia  (K).  To  see  the  cilia  it  is  necessary 
to  kill  the  spermatozoids  with  iodine  or  some  other  reagent. 

After  fertilization  the  outer  cells  of  the  oogonium  become  very  hard,  and 
the  whole  falls  off,  germinating  after  a  sufficient  period  of  rest. 

According  to  the  accounts  of  Pringsheim  and  others,  the 
young  plant  consists  at  first  of  a  row  of  elongated  cells,  upon 
which  a  bud  is  formed  that  develops  into  the  perfect  plant. 

There  are  two  families  of  the  Characece,  the  Charece,  of 
which  Chara  is  the  type,  and  the  Nitellece,  represented  by 
various  species  of  Nitella  and  Tolypella.  The  second  family 
have  the  internodes  without  any  cortex — that  is,  consisting 
of  a  single  long  cell ;  and  the  crown  at  the  top  of  the  oogo- 
nium is  composed  of  ten  cells  instead  of  five.  They  are  also 
destitute  of  the  limy  coating  of  the  Charece. 

Both  as  regards  the  structure  of  the  plant  itself,  as  well  as 
the  reproductive  organs,  especially  the  very  complex  antheri- 
dium, the  Characece,  are  very  widely  separated  from  any  other 
group  of  plants,  either  above  or  below  them. 


CHAPTER  VI. 

THE  BROWN   ALG-SJ  (Phoeophycece}. 

THESE  plants  are  all  characterized  by  the  presence  of  a 
brown  pigment,  in  addition  to  the  chlorophyll,  which  almost 
entirely  conceals  the  latter,  giving  the  plants  a  brownish  color, 
ranging  from  a  light  yellowish  brown  to  nearly  black.  One 
order  of  plants  that  possibly  belongs  here  (Diatomacece)  are 
single  celled,  but  the  others  are  for  the  most  part  large  sea- 
weeds. The  diatoms,  which  are  placed  in  this  class  simply  on 
account  of  the  color,  are  probably  not  closely  related  to  the 


FIG.  24. —  Forms  of  diatoms.  A,  Pinnularia.  i,  seen  from  above ;  n,  from  the 
side.  B,  Fragillaria  (?).  C,  Navicula.  D,  F,  Eunotia.  E,  Gomphonema. 
G,  Cocconeis.  H,  Diatoma.  All  x  300. 

other  brown  algae,  but  just  where  they  should  be  placed  is 
difficult  to  say.  In  some  respects  they  approach  quite  closely 
the  desmids,  and  are  not  infrequently  regarded  as  related  to 
them.  They  are  among  the  commonest  of  organisms  occur- 
ring everywhere  in  stagnant  and  running  water,  both  fresh 

41 


42 


BOTANY. 


and  salt,  forming  usually,  slimy,  yellowish  coatings  on  stones, 
mud,  aquatic  plants,  etc.     Like  the  desmids  they  may  be  sin- 
gle or  united  into  filaments,  and  not 
infrequently  are  attached  by  means  of 
a  delicate  gelatinous  stalk  (Fig.  25). 

They  are  at  once  distinguished  from  the 
desmids  by  their  color,  which  is  always 
some  shade  of  yellowish  or  reddish  brown. 
The  commonest  forms,  e.g.  Navicula  (Fig. 
24,  (7),  are  boat- shaped  when  seen  from 
above,  but  there  is  great  variety  hi  this 
respect.  The  cell  wall  is  always  impregnated 
with  large  amounts  of  flint,  so  that  after  the 
cell  dies  its  shape  is  perfectly  preserved,  the 
flint  making  a  perfect  cast  of  it,  looking 
like  glass.  These  flinty  shells  exhibit  won- 
derfully beautiful  and  delicate  markings 

which  are  sometimes  so  fine  as  to  test  the  best  lenses  to  make  them 

out. 

This  shell  is  composed  of  two  parts,  one  shutting  over  the  other  like  a 

pill  box  and  its  cover.     This  arrangement  is  best  seen  in  such  large  forms 

as  Pinnularia  (Fig.  24,  A  n). 

Most  of  the  diatoms  show  movements,  swimming  slowly  or 
gliding  over  solid  substances ;  but  like  the  movements  of  Oscil- 
laria  and  the  desmids,  the  movements  are  not  satisfactorily 
understood,  although  several  explanations  have  been  offered. 

They  resemble  somewhat  the  desmids  in  their  reproduction. 


FIG.  25.  —  Diatoms  attached 
by  a  gelatinous  stalk, 
x  150. 


THE  TRUE  BROWN  ALG^E. 

These  are  all  marine  forms,  many  of  great  size,  reaching  a 
length  in  some  cases  of  a  hundred  metres  or  more,  and  show- 
ing a  good  deal  of  differentiation  in  their  tissues  and  organs. 

One  of  the  commonest  forms  is  the  ordinary  rock  weed 
(Fucus),  which  covers  the  rocks  of  our  northeastern  coast  with 
a  heavy  drapery  for  several  feet  above  low-water  mark,  so  that 


THE  BEOWN  SEAWEEDS. 


43 


the  plants  are  completely  exposed  as  the  tide  recedes.  The 
commonest  species,  F.  vesiculosus  (Fig.  26,  A),  is  distinguished 
by  the  air  sacs  with  which  the  stems  are  provided.  The  plant 
is  attached  to  the  rock  by  means  of  a  sort  of  disc  or  root  from 
which  springs  a  stem  of  tough,  leathery  texture,  and  forking 
regularly  at  intervals,  so  that  the  ultimate  branches  are  very 


/an. 


FIG.  26.  —  A,  a  branch  of  common  rock  weed  (Fucus} ,  one-half  natural  size,  x, 
end  of  a  branch  bearing  conceptacles.  B,  section  through  a  conceptacle  con- 
taining oogonia  (og.},  x  25.  C,  E,  successive  stages  in  the  development  of 
the  oogonium,  x  150.  F,  G,  antheridia.  In  G,  one  of  the  antheridia  has  dis- 
charged the  mass  of  spermatozoids  (an.),  x  150. 

numerous,  and  the  plant  may  reach  a  length  of  a  metre  or 
more.  The  branches  are  flattened  and  leaf-like,  the  centre 
traversed  by  a  thickened  midrib.  The  end  of  the  growing 
branches  is  occupied  by  a  transversely  elongated  pit  or  de- 
pression. The  growing  point  is  at  the  bottom  of  this  pit, 
and  by  a  regular  forking  of  the  growing  point  the  symmetrical 


44  BOTANY. 

branching  of  the  plant  is  brought  about.  Scattered  over  the 
surface  are  little  circular  pits  through  whose  openings  pro- 
trude bunches  of  fine  hairs.  When  wet  the  plant  is  flexible 
and  leathery,  but  it  may  become  quite  dry  and  hard  without 
suffering,  as  may  be  seen  when  the  plants  are  exposed  to  the 
sun  at  low  tide. 

The  air  bladders  are  placed  in  pairs,  for  the  most  part,  and 
buoy  up  the  plant,  bringing  it  up  to  the  surface  when  covered 
with  water. 

The  interior  of  the  plant  is  very  soft  and  gelatinous,  while 
the  outer  part  forms  a  sort  of  tough  rind  of  much  firmer  con- 
sistence. The  ends  of  some  of  the  branches  (Fig.  26,  A,  x) 
are  usually  much  swollen,  and  the  surface  covered  with  little 
elevations  from  which  may  often  be  seen  protruding  clusters 
of  hairs  like  those  arising  from  the  other  parts  of  the  plant. 
A  section  through  one  of  these  enlarged  ends  shows  that  each 
elevation  corresponds  to  a  cavity  situated  below  it.  On  some 
of  the  plants  these  cavities  are  filled  with  an  orange-yellow 
mass ;  in  others  there  are  a  number  of  roundish  olive-brown 
bodies  large  enough  to  be  easily  seen.  The  yellow  masses  are 
masses  of  antheridia ;  the  round  bodies,  the  oogonia. 

If  the  plants  are  gathered  while  wet,  and  packed  so  as  to 
prevent  evaporation  of  the  water,  they  will  keep  perfectly  for 
several  days,  and  may  readily  be  shipped  for  long  distances. 
If  they  are  to  be  studied  away  from  the  seashore,  sections  for 
microscopic  examination  should  be  mounted  in  salt  water 
(about  3  parts  in  weight  of  common  salt  to  100  of  water).  If 
fresh  material  is  not  to  be  had,  dried  specimens  or  alcoholic 
material  will  answer  pretty  well. 

To  study  the  minute  structure  of  the  plant,  make  a  thin  cross- section, 
and  mount  in  salt  water.  The  inner  part  or  pith  is  composed  of  loosely 
arranged,  elongated  cells,  placed  end  to  end,  and  forming  an  irregular  net- 
work, the  large  spaces  between  filled  with  the  mucilaginous  substance 
derived  from  the  altered  outer  walls  of  these  cells.  This  mucilage  is  hard 
when  dry,  but  swells  up  enormously  in  water,  especially  fresh  water. 


THE  BROWN   SEAWEEDS.  45 

The  cells  grow  smaller  and  more  compact  toward  the  outside  of  the  section, 
until  there  are  no  spaces  of  any  size  between  those  of  the  outside  or  rind. 
The  cells  contain  small  chloroplasts  like  those  of  the  higher  plants,  but 
owing  to  the  presence  of  the  brown  pigment  found  in  all  of  the  class,  in 
addition  to  the  chlorophyll,  they  appear  golden  brown  instead  of  green. 

No  non-sexual  reproductive  bodies  are  known  in  the  rock  weeds,  beyond 
small  branches  that  occur  in  clusters  on  the  margins  of  the  main  branches, 
and  probably  become  detached,  forming  new  plants.  In  some  of  the  lower 
forms,  however,  e.g.  EctocarpusandLaminaria  (Fig.  28,  J.,  <7),  zoospores 
are  formed. 

The  sexual  organs  of  the  rock  weed,  as  we  have  already  seen,  are  borne 
in  special  cavities  (conceptacles)  in  the  enlarged  ends  of  some  of  the 
branches.  In  the  species  here  figured,  F.  vesiculosus,  the  antheridia  and 
oogonia  are  borne  on  separate  plants  ;  but  in  others,  e.g.  F.  platycarpus, 
they  are  both  in  the  same  conceptacle. 

The  walls  of  the  conceptacle  (Fig.  26,  B)  are  composed  of  closely  inter- 
woven filaments,  from  which  grow  inward  numerous  hairs,  filling  up  the 
space  within,  and  often  extending  out  through  the  opening  at  the  top. 

The  reproductive  bodies  arise  from  the  base  of  these  hairs.  The 
oogonia  (Fig.  26,  (7,  E)  arise  as  nearly  colorless  cells,  that  early  be- 
come divided  into  two  cells,  a  short  basal  cell  or  stalk  and  a  larger  ter- 
minal one,  the  oogonium  proper.  The  latter  enlarges  rapidly,  and  its 
contents  divide  into  eight  parts.  The  division  is  at  first  indicated  by  a 
division  of  the  central  portion,  which  includes  the  nucleus,  and  is  col- 
ored brown,  into  two,  four,  and  finally  eight  parts,  after  which  walls  are 
formed  between  these.  The  brown  color  spreads  until  the  whole  oogonium 
is  of  a  nearly  uniform  olive-brown  tint. 

When  ripe,  the  upper  part  of  the  oogonium  dissolves,  allowing  the 
eight  cells,  still  enclosed  in  a  delicate  membrane,  to  escape  (Fig.  27,  H). 
Finally,  the  walls  separating  the  inner  cells  of  the  oogonium  become  also 
absorbed,  as  well  as  the  surrounding  membrane,  and  the  eight  egg  cells 
escape  into  the  water  (Fig.  27,  7)  as  naked  balls  of  protoplasm,  in  which 
a  central  nucleus  may  be  dimly  seen. 

The  antheridia  (Fig.  26,  F,  G)  are  small  oblong  cells,  at  first  colorless, 
but  when  ripe  containing  numerous  glistening,  reddish  brown  dots,  each 
of  which  is  part  of  a  spermatozoid.  When  ripe,  the  contents  of  the 
antheridium  are  forced  out  into  the  water  (Cr),  leaving  the  empty  outer 
wall  behind,  but  still  surrounded  by  a  thin  membrane.  After  a  few 
minutes  this  membrane  is  dissolved,  and  the  spermatozoids  are  set  free. 
These  (Fig.  27,  A')  are  oval  in  form,  with  two  long  cilia  attached  to  the 


46 


BOTANY. 


side  where  the  brown  speck,  seen  while  still  within  the  antheridium,  is  con- 
spicuous. 

The  act  of  fertilization  may  be  easily  observed  by  laying  fresh  anthe- 
ridia  into  a  drop  of  water  containing  recently  discharged  egg  cells.     To 

obtain  these,  all  that 
is  necessary  is  to  al- 
low freshly  gathered 
plants  to  remain  in 
the  air  until  they  are 
somewhat  dry,  when 
the  ripe  sexual  cells 
will  be  discharged 
from  the  openings  of 
the  conceptacles,  ex- 
uding as  little  drops, 
those  with  antheridia 
being  orange-yellow; 
the  masses  of  oogonia, 
olive.  Within  a  few 
minutes  after  putting 
the  oogonia  into  water, 
the  egg  cells  may  be 
seen  to  escape  into  the 
water,  when  some  of 

the  antheridia  may  be 
FIG  27.  -  H,  the  eight  egg  cells  still  surrounded  by       ^ded      The  sperma. 
the  inner  membrane  of  the  oogomum.    7,  the  egg 

cells  escaping  into  the  water.  J,  a  single  egg  cell  tozoids  will  be  quickly 
surrounded  by  spermatozoids.  K,  mass  of  sperma-  discharged,  and  collect 
tozoids  surrounded  by  the  inner  membrane  of  the  .  ,.  ,  , 

antheridium.  L,  spermatozoids.  M,  young  plant.  immediately  in  great 
r,  the  roots.  K,  x  300  ;  L,  x  600  ;  the  others,  x  150.  numbers  about  the  egg 

cells,   to  which  they 

apply  themselves  closely,  often  setting  them  in  rotation  by  the  movements 
of  their  cilia,  and  presenting  a  most  extraordinary  spectacle  (J).  Owing  to 
the  small  size  of  the  spermatozoids,  and  the  opacity  of  the  eggs,  it  is  im- 
possible to  see  whether  more  than  one  spermatozoid  penetrates  it ;  but 
from  what  is  known  in  other  cases  it  is  not  likely.  The  egg  now  secretes 
a  wall  about  itself,  and  within  a  short  time  begins  to  grow.  It  becomes 
pear-shaped,  the  narrow  portion  becoming  attached  to  the  parent  plant  or 
to  some  other  object  by  means  of  rootlets,  and  the  upper  part  grows  into 
the  body  of  the  young  plant  (Fig.  27,  M).  — * 


THE  BROWN  SEAWEEDS.  47 

The  simpler  brown  seaweeds,  so  far  as  known,  multiply  only 
by  means  of  zoospores,  which  may  grow  directly  into  new 
plants,  or,  as  has  been  observed  in  some  species,  two  zoo'spores 
will  first  unite.  A  few,  like  Ectocarpus  (Fig.  28,  A),  are 
simple,  branched  filaments,  but  most  are  large  plants  with 
complex  tissues.  Of  the  latter,  a  familiar  example  is  the 


FIG.  28.  —  Forms  of  brown  seaweeds.  A,  Ectocarpus,  x  50.  Sporangia  (sp.). 
B,  a  single  sporangium,  x  150.  C,  kelp  (Laminaria),  x  %.  D,  E,  gulf  weed 
(Sargassum).  D,  one-half  natural  size.  Et  natural  size,  v,  air  bladders. 
x,  conceptacle  bearing  branches. 

common  kelp,  "  devil's  apron "  (Laminaria),  often  three  to 
four  metres  in  length,  with  a  stout  stalk,  provided  with  root- 
like  organs,  by  which  it  is  firmly  fastened.  Above,  it  expands 
into  a  broad,  leaf-like  frond,  which  in  some  species  is  divided 
into  strips.  Kelated  to  the  kelps  is  the  giant  kelp  of  the 
Pacific  (Macrocystis),  which  is  said  sometimes  to  reach  a  length 
of  three  hundred  metres. 


48  BOTANY. 

The  highest  of  the  class  are  the  gulf  weeds  (Sargassum), 
plants  of  the  warmer  seas,  but  one  species  of  which  is  found 
from  Cape  Cod  southward  (Fig.  28,  D,  E}.  These  plants 
possess  distinct  stems  and  leaves,  and  there  are  stalked  air 
bladders,  looking  like  berries,  giving  the  plant  a  striking 
resemblance  to  the  higher  land  plants. 


CHAPTER   VII. 
CLASS  III.  —  THE  BED  ALG^E  (Wiodophycece) . 

THESE  are  among  the  most  beautiful  and  interesting  mem- 
bers of  the  plant  kingdom,  both  on  account  of  their  beautiful 
colors  and  the  exquisitely  graceful  forms  exhibited  by  many 
of  them.  Unfortunately  for  inland  students  they  are,  with 
few  exceptions,  confined  to  salt  water,  and  consequently  fresh 
material  is  not  available.  Nevertheless,  enough  can  be  done 
with  dried  material  to  get  a  good  idea  of  their  general  appear- 
ance, and  the  fruiting  plants  can  be  readily  preserved  in  strong 
alcohol.  Specimens,  simply  dried,  may  be  kept  for  an  indefi- 
nite period,  and  on  being  placed  in  water  will  assume  perfectly 
the  appearance  of  the  living  plants.  Prolonged  exposure,  how- 
ever, to  the  action  of  fresh  water  extracts  the  red  pigment 
that  gives  them  their  characteristic  color.  This  pigment  is 
found  in  the  chlorophyll  bodies,  and  usually  quite  conceals  the 
chlorophyll,  which,  however,  becomes  evident  so  soon  as  the 
red  pigment  is  removed. 

The  red  seaweeds  differ  much  in  the  complexity  of  the 
plant  body,  but  all  agree  in  the  presence  of  the  red  pigment, 
and,  at  least  in  the  main,  in  their  reproduction.  The  simpler 
ones  consist  of  rows  of  cells,  usually  branching  like  Clado- 
phora;  others  form  cell  plates  comparable  to  Ulva  (Fig.  30, 
(7,  D)  ;  while  others,  among  which  is  the  well-known  Irish 
moss  (Cfltondrus),  form  plants  of  considerable  size,  with  pretty 
well  differentiated  tissues.  In  such  forms  the  outer  cells  are 
smaller  and  firmer,  constituting  a  sort  of  rind ;  while  the  inner 
portions  are  made  up  of  larger  and  looser  cells,  and  may  be 
called  the  pith.  Between  these  extremes  are  all  intermediate 
forms. 

49 


50 


BOTANY. 


They  usually  grow  attached  to  rocks,  shells,  wood,  or  other 
plants,  such  as  the  kelps  and  even  the  larger  red  seaweeds. 
They  are  most  abundant  in  the  warmer  seas,  but  still  a  con- 
siderable number  may  be  found  in  all  parts  of  the  ocean,  even 
extending  into  the  Arctic  regions. 


FIG.  29.—  A,  a  red  seaweed  (Callithamnion) ,  of  the  natural  size.  B,  a  piece  of 
the  same,  x  50.  t,  tetraspores.  C  i-v,  successive  stages  in  the  development 
of  the  tetraspores,  x  150.  D  i,  n,  young  procarps.  tr.  trichogyne.  in, 
young;  iv,  ripe  spore  fruit,  i,  in,  x  150.  iv,  x  50.  E,  an  antheridium, 
x  150.  F,  spore  fruit  of  Polysiphonia.  The  spores  are  here  surrounded  by 
a  case,  x  50. 

The  methods  of  reproduction  may  be  best  illustrated  by  a 
specific  example,  and  preferably  one  of  the  simpler  ones,  as 
these  are  most  readily  studied  microscopically. 

The  form  here  illustrated  (Callithamnion)  grows  attached  to 
wharves,  etc.,  below  low-water  mark,  and  is  extremely  delicate, 
collapsing  completely  when  removed  from  the  water.  The 
color  is  a  bright  rosy  red,  and  with  its  graceful  form  and  ex- 
treme delicacy  it  makes  one  of  the  most  beautiful  of  the  group. 


THE  RED  ALG^.  51 

If  alcoholic  material  is  used,  it  may  be  mounted  for  exami- 
nation either  in  water  or  very  dilute  glycerine. 

The  plant  is  composed  of  much-branched,  slender  filaments,  closely 
resembling  Cladophora  in  structure,  but  with  smaller  cells  (Fig.  29, 
S).  The  non- sexual  reproduction  is  by  means  of  special  spores,  which 
from  being  formed  in  groups  of  four,  are  known  as  tetraspores.  In  the 
species  under  consideration  the  mother  cell  of  the  tetraspores  arises  as  a 
small  bud  near  the  upper  end  of  one  of  the  ordinary  cells  (Fig.  29,  G  i). 
This  bud  rapidly  increases  in  size,  assuming  an  oval  form,  and  becoming 
cut  off  from  the  cell  of  the  stem  (Fig.  29,  C  n).  The  contents  now 
divide  into  four  equal  parts,  arranged  like  the  quadrants  of  a  sphere. 
When  ripe,  the  wall  of  the  mother  cell  gives  way,  and  the  four  spores 
escape  into  the  water  and  give  rise  to  new  plants.  These  spores,  it  will 
be  noticed,  differ  in  one  important  particular  from  corresponding  spores 
in  most  algae,  in  being  unprovided  with  cilia,  and  incapable  of  spontaneous 
movement. 

Occasionally  in  the  same  plant  that  bears  tetraspores,  but  more 
commonly  in  special  ones,  there  are  produced  the  sexual  organs,  and 
subsequently  the  sporocarps,  or  fruits,  developed  from  them.  The  plants 
that  bear  them  are  usually  stouter  that  the  non- sexual  ones,  and  the 
masses  of  ripe  carpospores  are  large  enough  to  be  readily  seen  with  the 
naked  eye. 

If  a  plant  bearing  ripe  spores  is  selected,  the  young  stages  of  the  female 
organ  (procarp)  may  generally  be  found  by  examining  the  younger  parts 
of  the  plant.  The  procarp  arises  from  a  single  cell  of  the  filament.  This 
cell  undergoes  division  by  a  series  of  longitudinal  walls  into  a  central  cell 
and  about  four  peripheral  ones  (Fig.  29,  D  i).  One  of  the  latter  divides 
next  into  an  upper  and  a  lower  cell,  the  former  growing  out  into  a  long, 
colorless  appendage  known  as  a  trichogyne  (Fig.  29,  Z),  tr.). 

The  antheridia  (Fig.  29,  E)  are  hemispherical  masses  of  closely  set 
colorless  cells,  each  of  which  develops  a  single  spermatozoid  which,  like 
the  tetraspores,  is  destitute  of  cilia,  and  is  dependent  upon  the  move- 
ment of  the  water  to  convey  it  to  the  neighborhood  of  the  procarp.  Occa- 
sionally one  of  these  spermatozoids  may  be  found  attached  to  the  tri- 
chogyne, and  in  this  way  fertilization  is  effected.  Curiously  enough, 
neither  the  cell  which  is  immediately  fertilized,  nor  the  one  beneath  it, 
undergo  any  further  change  ;  but  two  of  the  other  peripheral  cells  on  op- 
posite sides  of  the  filament  grow  rapidly  and  develop  into  large,  irregular 
masses  of  spores  (Fig.  29,  D  in,  iv). 


52  BOTANY, 

While  the  plant  here  described  may  be  taken  as  a  type  of 
the  group,  it  must  be  borne  in  mind  that  many  of  them  differ 
widely,  not  only  in  the  structure  of  the  plant  body,  but  in  the 
complexity  of  the  sexual  organs  and  spores  as  well.  The 
tetraspores  are  often  imbedded  in  the  tissues  of  the  plant,  or 
may  be  in  special  receptacles,  nor  are  they  always  arranged 


FIG.  30.  — Marine  red  seaweeds.  A,  Dasya.  B,  Rhodymenia  (with  smaller 
algse  attached).  C,  Grinnellia.  D,  Delesseria.  A,  B,  natural  size ;  the 
others  reduced  one-half. 

in  the  same  way  as  here  described,  and  the  same  is  true  of  the 
carpospores.  These  latter  are  in  some  of  the  higher  forms, 
e.g.  Potysiphonia  (Fig.  29,  F),  contained  in  urn-shaped  recepta- 
cles, or  they  may  be  buried  within  the  tissues  of  the  plant. 

The  fresh-water  forms  are  not  common,  but  may  occasionally 
be  met  with  in  mill  streams  and  other  running  water,  attached 
to  stones  and  woodwork,  but  are  much  inferior  in  size  and 


THE  RED 


53 


beauty  to  the  marine  species.     The  red  color  is  not  so  pro- 
nounced,  and    they  are,    as  a  rule,   somewhat   dull   colored. 


FIG.  31.  —  Fresh- water  red  algae.    A,  Batrachospermum,  x  about  12.    B,  a 
branch  of  the  same,  x  150.    C,  Lemanea,  natural  size. 

The   commonest   genera  are  Batrachospermum   and  Lemanea 
(Fig.  31). 


CHAPTER   VIII. 


SUB-KINGDOM  III. 
FUNGI. 

THE  name  "  Fungi "  has  been  given  to  a  vast  assemblage  of 
plants,  varying  much  among  themselves,  but  on  the  whole  of 
about  the  same  structural  rank  as  the  algae.  Unlike  the 
algae,  however,  they  are  entirely  destitute  of  chlorophyll,  and 
in  consequence  are  dependent  upon  organic  matter  for  food, 
some  being  parasites  (growing  upon  living  organisms),  others 
saprophytes  (feeding  on  dead  matter).  Some  of  them  show 
close  resemblances  in  structure  to  certain  algae,  and  there  is 
reason  to  believe  that  they  are  descended  from  forms  that 
originally  had  chlorophyll  j  others  are  very  different  from  any 
green  plants,  though  more  or  less  evidently  related  among 
themselves.  Recognizing  then  these  distinctions,  we  may 
make  two  divisions  of  the  sub-kingdom  :  I.  The  Algo-Fungi 
(Phycomycetes),  and  II.  The  True  Fungi  (Mycomycetes}. 

CLASS  I.  —  Phy corny cetes. 

These  are  fungi  consisting  of  long,  undivided,  often  branch- 
ing tubular  filaments,  resembling  quite  closely  those  of  Vau- 
cheria  or  other  Slphonece,  but  always  destitute  of  any  trace  of 
chlorophyll.  The  simplest  of  these  include  the  common  moulds 
(Mucorini),  one  of  which  will  serve  to  illustrate  the  character- 
istics of  the  order. 

If  a  bit  of  fresh  bread,  slightly  moistened,  is  kept  under  a 
U 


FUNGI.  55 

bell  jar  or  tumbler  in  a  warm  room,  in  the  course  of  twenty- 
four  hours  or  so  it  will  be  covered  with  a  film  of  fine  white 
threads,  and  a  little  later  will  produce  a  crop  of  little  globular 
bodies  mounted  on  upright  stalks.  These  are  at  first  white, 
but  soon  become  black,  and  the  filaments  bearing  them  also 
grow  dark-colored. 

These  are  moulds,  and  have  grown  from  spores  that  are  in 
the  atmosphere  falling  on  the  bread,  which  offers  the  proper 
conditions  for  their  growth  and  multiplication. 

One  of  the  commonest  moulds  is  the  one  here  figured  (Fig. 
32),  and  named  Mucor  stolonifer,  from  the  runners,  or  "stolons," 
by  which  it  spreads  from  one  point  to  another.  As  it  grows 
it  sends  out  these  runners  along  the  surface  of  the  bread,  or 
even  along  the  inner  surface  of  the  glass  covering  it.  They 
fasten  themselves  at  intervals  to  the  substratum,  and  send  up 
from  these  points  clusters  of  short  filaments,  each  one  tipped 
with  a  spore  case,  or  "  sporangium." 

For  microscopical  study  they  are  best  mounted  in  dilute  glycerine 
(about  one-quarter  glycerine  to  three-quarters  pure  water).  After  care- 
fully spreading  out  the  specimens  in  this  mixture,  allow  a  drop  of  alcohol 
to  fall  upon  the  preparation,  and  then  put  on  the  cover  glass.  The  alcohol 
drives  out  the  air,  which  otherwise  interferes  badly  with  the  examina- 
tion. 

The  whole  plant  consists  of  a  very  long,  much-branched,  but  undivided 
tubular  filament.  Where  it  is  in  contact  with  the  substratum,  root-like 
outgrowths  are  formed,  not  unlike  those  observed  in  Vaucheria.  At  first 
the  walls  are  colorless,  but  later  become  dark  smoky  brown  in  color. 
A  layer  of  colorless  granular  protoplasm  lines  the  wall,  becoming  more 
abundant  toward  the  growing  tips  of  the  branches.  The  spore  cases, 
"sporangia,"  arise  at  the  ends  of  upright  branches  (Fig.  32,  O),  which  at 
first  are  cylindrical  (a),  but  later  enlarge  at  the  end  (6),  and  become  cut 
off  by  a  convex  wall  (c).  This  wall  pushes  up  into  the  young  sporangium, 
forming  a  structure  called  the  "columella."  When  fully  grown,  the 
sporangium  is  globular,  and  appears  quite  opaque,  owing  to  the  numerous 
granules  in  the  protoplasm  filling  the  space  between  the  columella  and 
its  outer  wall.  This  protoplasm  now  divides  into  a  great  number  of  small 
oval  cells  (spores),  which  rapidly  darken,  owing  to  a  thick,  black  wall 


56 


BOTANY. 


formed  about  each  one,  and  at  the  same  time  the  columella  and  the  stalk 
of  the  sporangium  become  dark- colored. 

When  ripe,  the  wall  of  the  sporangium  dissolves,  and  the  spores  (Fig. 
32,  E)  are  set  free.  The  columella  remains  unchanged,  and  some  of  the 
spores  often  remain  sticking  to  it  (Fig.  32,  D). 


FIG.  32.  —  ^!,  common  black  mould  (Mwcor),  x  5.  B,  three  nearly  ripe  spore 
cases,  x  25.  C,  development  of  the  spore  cases,  i-iv,  x  150 ;  v,  x  50.  Z),  spore 
case  which  has  discharged  its  spores.  E,  spores,  x  300.  F,  a  form  of  Mucor 
miicedo,  with  small  accessory  spore  cases,  x  5.  G,  the  spore  cases,  x  50.  H,  a 
single  spore  case,  x  300.  I,  development  of  the  zygospore  of  a  black  mould, 
x  45  (after  DeBary). 

Spores  formed  in  a  manner  strongly  recalling  those  of  the  pond  scums 
are  also  known,  but  only  occur  after  the  plants  have  grown  for  a  long 
time,  and  hence  are  rarely  met  with  (Fig.  32,  7). 

Another  common  mould  (M.  mucedo),  often  growing  in  com- 
pany with,  the  one  described,  differs  from  it  mainly  in  the 
longer  stalk  of  the  sporangium,  which  is  also  smaller,  and  in 
not  forming  runners.  This  species  sometimes  bears  clusters  of 
very  small  sporangia  attached  to  the  middle  of  the  ordinary 


FUNGI.  57 

sporangial  filament  (Fig.  32,  F,  H).  These  small  sporangia 
have  no  columella. 

Other  moulds  are  sometimes  met  with,  parasitic  upon  the 
larger  species  of  Mucor. 

Related  to  the  black  moulds  are  the  insect  moulds  (Ento- 
mopthorece),  which  attack  and  destroy  insects.  The  commonest 
of  these  attacks  the  house  flies  in  autumn,  when  the  flies,  thus 
infested,  may  often  be  found  sticking  to  window  panes,  and 
surrounded  by  a  whitish  halo  of  the  spores  that  have,  been 
thrown  off  by  the  fungus. 


ORDER  II.  —  WHITE  BUSTS  AND  MILDEWS  (Peronosporece) 

These  are  exclusively  parasitic  fungi,  and  grow  within  the 
tissues  of  various  flowering  plants,  sometimes  entirely  destroy- 
ing them. 

As  a  type  of  this  group  we  will  select  a  very  common  one 
(Oystopus  bliti),  that  is  always  to  be  found  in  late  summer  and 
autumn  growing  on  pig  weed  (Amarantus).  It  forms  whitish, 
blister-like  blotches  about  the  size  of  a  pin  head  on  the  leaves 
and  stems,  being  commonest  on  the  under  side  of  the  leaves 
(Fig.  33,  A).  In  the  earlier  stages  the  leaf  does  not  appear 
much  affected,  but  later  becomes  brown  and  withered  about 
the  blotches  caused  by  the  fungus. 

If  a  thin  vertical  section  of  the  leaf  is  made  through  one  of  these 
blotches,  and  mounted  as  described  for  Mucor,  the  latter  is  found  to  be 
composed  of  a  mass  of  spores  that  have  been  produced  below  the  epidermis 
of  the  leaf,  and  have  pushed  it  up  by  their  growth.  If  the  section  is  a 
very  thin  one,  we  may  be  able  to  make  out  the  structure  of  the  fungus, 
and  then  find  it  to  be  composed  of  irregular,  tubular,  much- branched  fila- 
ments, which,  however,  are  not  divided  by  cross-walls.  These  filaments 
run  through  the  intercellular  spaces  of  the  leaf,  and  send  into  the  cells 
little  globular  suckers,  by  means  of  which  the  fungus  feeds. 

The  spores  already  mentioned  are  formed  at  the  ends  of  crowded  fila- 
ments, that  push  up,  and  finally  rupture  the  epidermis  (Fig.  33,  B).  They 


58 


BOTANY. 


are  formed  by  the  ends  of  the  filaments  swelling  up  and  becoming  con- 
stricted, so  as  to  form  an  oval  spore,  which  is  then  cut  off  by  a  wall.  The 
portion  of  the  filament  immediately  below  acts  in  the  same  way,  and  the 
process  is  repeated  until  a  chain  of  half  a  dozen  or  more  may  be  produced, 
the  lowest  one  being  always  the  last  formed.  When  ripe,  the  spores  are 
separated  by  a  thin  neck,  and  become  very  easily  broken  off. 

In  order  to  follow  their  germination  it  is  only  necessary  to  place  a  few 
leaves  with  fresh  patches  of  the  fungus  under  a  bell  jar  or  tumbler, 
inverted  over  a  dish  full  of  water,  so  as  to  keep  the  air  within  saturated 
with  moisture,  but  taking  care  to  keep  the  leaves  out  of  the  water.  After 


an. 


FIG.  33.  —  A,  leaf  of  pigweed  (Amarantus) ,  with  spots  of  white  rust  (c),  one- 
half  natural  size.  B,  non-sexual  spores  (conidia).  C,  the  same  germinat- 
ing. D,  zoospores.  E,  germinating  zoospores.  sp.  the  spore.  F,  young. 
G,  mature  sexual  organs.  In  G,  the  tube  may  be  seen  connecting  the 
antheridium  (an.),  with  the  egg  cell  (o).  H,  a  ripe  resting  spore  still 
surrounded  by  the  wall  of  the  oogonium.  7,  a  part  of  a  filament  of  the 
fungus,  showing  its  irregular  form.  All  x  300. 


about  twenty-four  hours,  if  some  of  the  spores  are  scraped  off  and 
mounted  in  water,  they  will  germinate  in  the  course  of  an  hour  or  so.  The 
contents  divide  into  about  eight  parts,  which  escape  from  the  top  of  the 
spore,  which  at  this  time  projects  as  a  little  papilla.  On  escaping,  each 
mass  of  protoplasm  swims  away  as  a  zoospore,  with  two  extremely  delicate 
cilia.  After  a  short  time  it  comes  to  rest,  and,  after  developing  a  thin 
cell  wall,  germinates  by  sending  out  one  or  two  filaments  (Fig.  33,  (7,  E). 
Under  normal  conditions  the  spores  probably  germinate  when  the  leaves 
are  wet,  and  the  filaments  enter  the  plant  through  the  breathing  pores  on 


FUNGI.  59 

the  lower  surface  of  the  leaves,  and  spread  rapidly  through  the  intercellu- 
lar spaces. 

Later  on,  spores  of  a  very  different  kind  are  produced.  Unlike  those 
already  studied,  they  are  formed  some  distance  below  the  epidermis,  and 
in  order  to  study  them  satisfactorily,  the  fungus  must  be  freed  from  the 
host  plant.  In  order  to  do  this,  small  pieces  of  the  leaf  should  be  boiled 
for  about  a  minute  in  strong  caustic  potash,  and  then  treated  with  acetic 
or  hydrochloric  acid.  By  this  means  the  tissues  of  the  leaf  become  so 
soft  as  to  be  readily  removed,  while  the  fungus  is  but  little  affected.  The 
preparation  should  now  be  washed  and  mounted  in  dilute  glycerine. . 

The  spores  (oospores)  are  much  larger  than  those  first  formed,  and 
possess  an  outer  coat  of  a  dark  brown  color  (Fig.  33,  H).  Each  spore  is 
contained  in  a  large  cell,  which  arises  as  a  swelling  of  one  of  the  filaments, 
and  becomes  shut  off  by  a  wall.  At  first  (Fig.  33,  F)  its  contents  are 
granular,  and  fill  it  completely,  but  later  contract  to  form  a  globular  mass 
of  protoplasm  (G.°),  the  germ  cell  or  egg  cell.  The  whole  is  an  oogonium, 
and  differs  in  no  essential  respect  from  that  of  Vaucheria. 

Frequently  a  smaller  cell  (antheridium),  arising  from  a  neighboring 
filament,  and  in  close  contact  with  the  oogonium,  may  be  detected  (Fig. 
33,  F,  G,  cm.),  and  in  exceptionally  favorable  cases  a  tube  is  to  be  seen 
connecting  it  with  the  germ  cell,  and  by  means  of  which  fertilization  is 
effected. 

After  being  fertilized,  the  germ  cell  secretes  a  wall,  at  first  thin  and 
colorless,  but  later  becoming  thick  and  dark-colored  on  the  outside,  and 
showing  a  division  into  several  layers,  the  outermost  of  which  is  dark 
brown,  and  covered  with  irregular  reticulate  markings.  These  spores  do 
not  germinate  at  once,  but  remain  over  winter  unchanged. 


FIG.  34. — Fragment  of  a  filament  of  the  white  rust  of  the  shepherd's-purse, 
showing  the  suckers  (7i),  x  300. 

It  is  by  no  means  impossible  that  sometimes  the  germ  cell 
may  develop  into  a  spore  without  being  fertilized,  as  is  the 
case  in  many  of  the  water  moulds. 


60 


BOTANY. 


Closely  related  to  the  species  above  described  is  another  one 
(C.  candidus),  which  attacks  shepherd's  -  purse,  radish,  and 
others  of  the  mustard  family,  upon  which  it  forms  chalky 
white  blotches,  and  distorts  the  diseased  parts  of  the  plant 
very  greatly. 

For  some  reasons  this  is  the  best  species 
for  study,  longitudinal  sections  through  the 
stem  showing  very  beautifully  the  structure 
of  the  fungus,  and  the  penetration  of  the 
cells  of  the  host1  by  the  suckers  (Fig.  34). 

Very  similar  to  the  white  rusts  in 
most  respects,  but  differing  in  the 
arrangement  of  the  non-sexual  spores, 
are  the  mildews  (Peronospora,  Phyto- 
phthora).  These  plants  form  mouldy- 
looking  patches  on  the  leaves  and 
stems  of  many  plants,  and  are  often 
very  destructive.  Among  them  are 
the  vine  mildew  (Peronospora  viti- 

cola)   (Fig.  35),  the  potato  fungus  (Phytophthora   infestans), 

and  many  others. 


spoi 

of  the  vine  mildew  (Pero- 
nospora viticola),  x  150. 


ORDER  III.  —  Saprolegniuceai  (WATER  MOULDS). 

These  plants  resemble  quite  closely  the  white  rusts,  and  are 
probably  related  to  them.  They  grow  on  decaying  organic 
matter  in  water,  or  sometimes  on  living  water  animals,  fish, 
crustaceans,  etc.  They  may  usually  be  had  for  study  by  throw- 
ing into  water  taken  from  a  stagnant  pond  or  aquarium,  a  dead 
fly  or  some  other  insect.  After  a  few  days  it  will  probably  be 
found  covered  with  a  dense  growth  of  fine,  white  filaments, 
standing  out  from  it  in  all  directions  (Fig.  36,  A) .  Somewhat 


Host,"  the  plant  or  animal  upon  which  a  parasite  lives. 


FUNGI. 


61 


later,  if  carefully  examined  with  a  lens,  little  round,  white 
bodies  may  be  seen  scattered  among  the  filaments. 


On  carefully  removing  a  bit  of  the  younger  growth  and  examining  it 
microscopically,  it  is  found  to  consist  of  long  filaments  much  like  those  of 
Vaucheria,  but  entirely  destitute  of  chlorophyll.  In  places  these  fila- 
ments are  filled  with  densely  granular  protoplasm,  which  when  highly 


FIG.  36.  —  A,  an  insect  that  has  decayed  in  water,  and  become  attacked  by  a 
water  mould  (Saproleynia) ,  natural  size.  B,  a  ripe  zoosporangium,  x  100. 
(7,  the  same  discharging  the  spores.  D,  active.  JE,  germinating  zoospores, 
x  300.  F,  a  second  sporangium  forming  below  the  empty  one.  G  i-iv, 
development  of  the  oogoniuin,  x  100.  H,  ripe  oogonium  filled  with  resting 
spores,  x  100. 

magnified  exhibits  streaming  movements.  The  protoplasm  contains  a  large 
amount  of  oil  in  the  form  of  small,  shining  drops. 

In  the  early  stages  of  its  growth  the  plant  multiplies  by  zoospores,  pro- 
duced in  great  numbers  in  sporangia  at  the  ends  of  the  branches.  The 
protoplasm  collects  here  much  as  we  saw  in  V.  sessilis,  the  end  of  the  fila- 
ment becoming  club-shaped  and  ending  in  a  short  protuberance  (Fig.  36, 
J5).  This  end  becomes  separated  by  a  wall,  and  the  contents  divide  into 
numerous  small  cells  that  sometimes  are  naked,  and  sometimes  have  a 
delicate  membrane  about  them.  The  first  sign  of  division  is  the  appear- 


62  BOTANY. 

ance  in  the  protoplasm  of  delicate  lines  dividing  it  into  numerous  polyg- 
onal areas  which  soon  become  more  distinct,  and  are  seen  to  be  distinct 
cells  whose  outlines  remain  more  or  less  angular  on  account  of  the  mutual 
pressure.  When  ripe,  the  end  of  the  sporangium  opens,  and  the  contained 
cells  are  discharged  (Fig.  36,  C).  In  case  they  have  no  membrane,  they  swim 
away  at  once,  each  being  provided  with  two  cilia,  and  resembling  almost 
exactly  the  zoospores  of  the  white  rust  (Fig.  36,  D,  E).  When  the  cells 
are  surrounded  by  a  membrane  they  remain  for  some  time  at  rest,  but 
finally  the  contents  escape  as  a  zoospore,  like  those  already  described. 
By  killing  the  zoospores  with  a  little  iodine  the  granular  nature  of  the 
protoplasm  is  made  more  evident,  and  the  cilia  may  be  seen.  They  soon 
come  to  rest,  and  germinate  in  the  same  way  as  those  of  the  white  rusts 
and  mildews. 

As  soon  as  the  sporangium  is  emptied,  a  new  one  is  formed,  either  by 
the  filament  growing  up  through  it  (Fig.  36,  F)  and  the  end  being  again 
cut  off,  or  else  by  a  branch  budding  out  just  below  the  base  of  the  empty 
sporangium,  and  growing  up  by  the  side  of  it. 

Besides  zoospores  there  are  also  resting  spores  developed.  Oogonia 
like  those  of  Vaucheria  or  the  Peronosporece  are  formed  usually  after  the 
formation  of  zoospores  has  ceased  ;  but  in  many  cases,  perhaps  all,  these 
develop  without  being  fertilized.  Antheridia  are  often  wanting,  and  even 
when  they  are  present,  it  is  very  doubtful  whether  fertilization  takes 
place.1 

The  oogonia  (Fig.  36,  6r,  II)  arise  at  the  end  of  the  main  filaments,  or 
of  short  side  branches,  very  much  as  do  the  sporangia,  from  which  they 
differ  at  this  stage  in  being  of  globular  form.  The  contents  contract  to 
form  one  or  several  egg  cells,  naked  at  first,  but  later  becoming  thick- 
walled  resting  spores  (//). 

1  The  antheridia,  when  present,  arise  as  branches  just  below  the  oogo- 
nium,  and  become  closely  applied  to  it,  sometimes  sending  tubes  through 
its  wall,  but  there  has  been  no  satisfactory  demonstration  of  an  actual 
transfer  of  the  contents  of  the  antheridium  to  the  egg  cell. 


CHAPTER   IX. 

THE   TRUE   FUNGI    (My corny cefes). 

THE  great  majority  of  the  plants  ordinarily  known  as  fungi 
are  embraced  under  this  head.  While  some  of  the  lower  forms 
show  affinities  with  the  Phycomycetes,  and  through  them  with 
the  algae,  the  greater  number  differ  very  strongly  from  all 
green  plants  both  in  their  habits  and  in  their  structure  and 
reproduction.  It  is  a  much-disputed  point  whether  sexual 
reproduction  occurs  in  any  of  them,  and  it  is  highly  probable 
that  in  the  great  majority,  at  any  rate,  the  reproduction  is 
purely  non-sexual. 

Probably  to  be  reckoned  with  the  Mycomycetes,  but  of  doubt- 
ful affinities,  are  the  small  unicellular  fungi  that  are  the  main 
causes  of  alcoholic  fermentation;  these  are  the  yeast  fungi 
(Saccharomycetes).  They  cause  the  fermentation  of  beer  and 
wine,  as  well  as  the  incipient  fermentation  in  bread,  causing  it 
to  "rise"  by  the  giving  off  of  bubbles  of  carbonic  acid  gas 
during  the  process. 

If  a  little  common  yeast  is  put  into  water  containing  starch 
or  sugar,  and  kept  in  a  warm  place,  in  a  short  time  bubbles  of 
gas  will  make  their  appearance,  and  after  a  little  longer  time 
alcohol  may  be  detected  by  proper  tests ;  in  short,  alcoholic 
fermentation  is  taking  place  in  the  solution. 

If  a  little  of  the  fermenting  liquid  is  examined  microscopically,  it  will 
be  found  to  contain  great  numbers  of  very  small,  oval  cells,  with  thin  cell 
walls  and  colorless  contents.  A  careful  examination  with  a  strong  lens 
(magnifying  from  500-1000  diameters)  shows  that  the  protoplasm,  in 
which  are  granules  of  varying  size,  does  not  fill  the  cell  completely,  but 
that  there  are  one  or  more  large  vacuoles  or  spaces  filled  with  colorless 

63 


64  BOTANY. 

cell  sap.     No  nucleus  is  visible  in  the  living  cell,  but  it  has  been  shown 

that  a  nucleus  is  present. 

If  growth  is  active,  many  of  the  cells  will  be  seen  dividing.  The 
process  is  somewhat  different  from  or- 
dinary fission  and  is  called  budding 
(Fig.  37,  .B).  A  small  protuberance  ap- 
pears at  the  bud  or  at  the  side  of  the  cell, 
and  enlarges  rapidly,  assuming  the  form 
of  the  mother  cell,  from  which  it  becomes 
completely  separated  by  the  constriction 
of  the  base,  and  may  fall  off  at  once,  or, 
as  is  more  frequently  the  case,  may  re- 
main attached  for  a  time,  giving  rise  itself 

to  other  buds'  so  that  not  "^frequently 
showing  the  process  of  bud-  groups  of  half  a  dozen  or  more  cells  are 
ding,  x  750.  met  with 


That  the  yeast  cells  are  the  principal  agents  of  alcoholic 
fermentation  may  be  shown  in  much  the  same  way  that  bac- 
teria are  shown  to  cause  ordinary  decomposition.  Liquids 
from  which  they  are  excluded  will  remain  unfermented  for 
an  indefinite  time. 

There  has  been  much  controversy  as  to  the  systematic  posi- 
tion of  the  yeast  fungi,  which  has  not  yet  been  satisfactorily 
settled,  the  question  being  whether  they  are  to  be  regarded 
as  independent  plants  or  only  one  stage  in  the  life  history  of 
some  higher  fungi  (possibly  the  /Smuts),  which  through  culti- 
vation have  lost  the  power  of  developing  further. 


CLASS  I. — THE  SMUTS  (Ustillaginece) . 

The  smuts  are  common  and  often  very  destructive  parasitic 
fungi,  living  entirely  within  the  tissues  of  the  higher  plants. 
Owing  to  this,  as  well  as  to  the  excessively  small  spores  and 
difficulty  in  germinating  them,  the  plants  are  very  difficult  of 
study,  except  in  a  general  way,  and  we  will  content  ourselves 
with  a  glance  at  one  of  the  common  forms,  the  corn  smut 


FUNGI. 


65 


(Ustillago  maydis).  This  familiar  fungus  attacks  Indian  corn, 
forming  its  spores  in  enormous  quantities  in  various  parts  of 
the  diseased  plant,  but  particularly  in  the  flowers  ("tassel" 
and  young  ear). 

The  filaments,  which  resemble  somewhat  those  of  the  white  rusts, 
penetrate  all  parts  of  the  plant,  and  as  the  time  approaches  for  the  forma- 
tion of  the  spores,  these  branch  ex- 
tensively, and  at  the  same  time  be- 
come soft  and  mucilaginous  (Fig.  38, 
Z2).  The  ends  of  these  short  branches 
enlarge  rapidly  and  become  shut  off 
by  partitions,  and  in  each  a  globular 
spore  (Fig.  38,  (7)  is  produced.  The 
outer  wall  is  very  dark-colored  and 
provided  with  short  spines.  To  study 
the  filaments  and  spore  formation, 
very  thin  sections  should  be  made 
through  the  young  kernels  or  other 
parts  in  the  vicinity,  before  they  are 
noticeably  distorted  by  the  growth  of 
the  spore-bearing  filaments. 


© 


FIG.  38. — A,"  tassel "  of  corn  attacked 
by  smut  (Ustillago).  B,  fila- 
ments of  the  fungus  from  a  thin 
section  of  a  diseased  grain,  show- 
ing the  beginning  of  the  formation 
of  the  spores,  x  300.  C,  ripe 
spores,  x  300. 


As  the  spores  are  forming,  an  abnormal  growth  is  set  up  in 
the  cells  of  the  part  attacked,  which  in  consequence  becomes 
enormously  enlarged  (Fig.  38,  A),  single  grains  sometimes 
growing  as  large  as  a  walnut.  As  the  spores  ripen,  the  affected 
parts,  which  are  at  first  white,  become  a  livid  gray,  due  to  the 
black  spores  shining  through  the  overlying  white  tissues. 
Finally  ^the  masses  of  spores  burst  through  the  overlying 
cells,  appearing  like  masses  of  soot,  whence  the  popular  name 
for  the  plant. 

The  remaining  Mycomycetes  are  pretty  readily  divisible  into 
two  great  classes,  based  upon  the  arrangement  of  the  spores. 
The  first  of  these  is  known  as  the  Ascomycetes  (Sac  fungi),  the 
other  the  Basidiomycetes  (mushrooms,  puff-balls,  etc.). 


66  BOTANY. 


CLASS  II. — Ascomycetes  (SAC  FUNGI). 

This  class  includes  a  very  great  number  of  common  plants, 
all  resembling  each  other  in  producing  spores  in  sacs  (asci, 
sing,  ascus)  that  are  usually  oblong  in  shape,  and  each  contain- 
ing eight  spores,  although  the  number  is  not  always  the  same. 
Besides  the  spores  formed  in  these  sacs  (ascospores),  there  are 
other  forms  produced  in  various  ways. 

There  are  two  main  divisions  of  the  class,  the  first  including 
only  a  few  forms,  most  of  which  are  not  likely  to  be  met  with 
by  the  student.  In  these  the  spore  sacs  are  borne  directly 
upon  the  filaments  without  any  protective  covering.  The  only 
form  that  is  at  all  common  is  a  parasitic  fungus  (Exoascus) 
that  attacks  peach-trees,  causing  the  disease  of  the  leaves 
known  as  "curl." 

All  of  the  common  Ascomycetes  belong  to  the  second  division, 
and  have  the  spore  sacs  contained  in  special  structures  called 
spore  fruits,  that  may  reach  a  diameter  of  several  centimetres 
in  a  few  cases,  though  ordinarily  much  smaller. 

Among  the  simpler  members  of  this  group  are  the  mildews 
(Perisporiacece) ,  mostly  parasitic  forms,  living  upon  the  leaves 
and  stems  of  flowering  plants,  sometimes  causing  serious  injury 
by  their  depredations.  They  form  white  or  grayish  downy 
films  on  the  surface  of  the  plant,  in  certain  stages  looking  like 
hoar-frost.  Being  very  common,  they  maybe  readily  obtained, 
and  are  easily  studied.  One  of  the  best  species  £f>r  study 
(Podosphcera)  grows  abundantly  on  the  leaves  of  the  dan- 
delion, especially  when  the  plants  are  growing  under  unfa- 
vorable conditions.  The  same  species  is  also  found  on  other 
plants  of  the  same  family.  It  may  be  found  at  almost  any 
time  during  the  summer;  but  for  studying,  the  spore  fruits 
material  should  be  collected  in  late  summer  or  early  autumn. 
It  at  first  appears  as  white,  frost-like  patches,  growing  dingier 
as  it  becomes  older,  and  careful  scrutiny  of  the  older  specimens 


FUNGI. 


67 


will  show  numerous  brown  or  blackish  specks   scattered  over 
the  patches.     These  are  the  spore  fruits. 

For  microscopical  study,  fresh  material  may  be  used,  or,  if  necessary, 
dried  specimens.  The  latter,  before  mounting,  should  be  soaked  for  a 
short  time  in  water,  to  which  has  been  added  a  few  drops  of  caustic-potash 


ar. 


FIG.  39.  —  A,  spore-bearing  filaments  of  the  dandelion  mildew  (Podosphssra), 
x  150.  B,  a  germinating  spore,  x  150.  C-F,  development  of  the  spore  fruit, 
x  300.  ar.  archicarp.  G,  a  ripe  spore  fruit,  x  150.  H,  the  spore  sac  removed 
from  the  spore  fruit,  x  150.  /,  spore-bearing  filament  attacked  by  another 
fungus  (Cicinnobulus) ,  causing  the  enlargement  of  the  basal  cell,  x  150. 
J,  a  more  advanced  stage,  x  300.  K,  spores,  x  300. 

solution.  This  will  remove  the  brittleness,  and  swell  up  the  dried  fila- 
ments to  their  original  proportions.  A  portion  of  the  plant  should  be 
carefully  scraped  off  the  leaf  on  which  it  is  growing,  thoroughly  washed  in 
pure  water,  and  transferred  to  a  drop  of  water  or  very  dilute  glycerine, 
in  which  it  should  be  carefully  spread  out  with  needles.  If  air  bubbles 
interfere  with  the  examination,  they  may  be  driven  off  with  alcohol,  and 
then  the  cover  glass  put  on.  If  the  specimen  is  mounted  in  glycerine,  it 
will  keep  indefinitely,  if  care  is  taken  to  seal  it  up.  The  plant  consists  of 


68  BOTANY. 

much- interlaced  filaments,  divided  at  intervals  by  cross-walls.1  They  are 
nearly  colorless,  and  the  contents  are  not  conspicuous.  These  filaments 
send  up  vertical  branches  (Fig.  39,  A),  that  become  divided  into  a  series 
of  short  cells  by  means  of  cross- walls.  The  cells  thus  formed  are  at  first 
cylindrical,  but  later  bulge  out  at  the  sides,  becoming  broadly  oval,  and 
finally  become  detached  as  spores  (conidia).  It  is  these  spores  that  give 
the  frosty  appearance  to  the  early  stages  of  the  fungus  when  seen  with  the 
naked  eye.  The  spores  fall  off  very  easily  when  ripe,  and  germinate 
quickly  in  water,  sending  out  two  or  more  tubes  that  grow  into  filaments 
like  those  of  the  parent  plant  (Fig.  39,  B). 

The  spore  fruits,  as  already  observed,  are  formed  toward  the  end  of  the 
season,  and,  in  the  species  under  consideration  at  least,  appear  to  be  the 

result  of  a  sexual  process.  The  sex- 
ual organs  (if  they  are  really  such) 
are  extremely  simple,  and,  owing  to 
their  very  small  size,  are  not  easily 
found.  They  arise  as  short  branches 
at  a  point  where  two  filaments  cross  ; 
one  of  them  (Fig.  39,  <7,  ar.),  the  fe- 
male cell,  or  "archicarp,"  is  some- 
what larger  than  the  other  and  nearly 
FIG.  40.  —  Chrysanthemum  mildew  „„„!  .•„  fmnY1  nTWi  ____.  ho™™oc 
(Erysiphe),  showing  the  suckers  OVal  m  10rm'  and  SOOn  becomes 
(h)  by  which  the  filaments  are  at-  separated  by  a  partition  from  the  fila- 
tached  to  the  leaf.  A  surface  ment  that  bears  it.  The  other  branch 
view.  5,  vertical  section  of  the  .  .,  .,.  x 

leaf,  x  300.  (antheridium)  grows  up  in  close  con- 

tact with  the  archicarp,  and  like  it  is 

shut  off  by  a  partition  from  its  filament.  It  is  more  slender  than  the 
archicarp,  but  otherwise  differs  little  from  it.  No  actual  communication 
can  be  shown  to  be  present  between  the  two  cells,  and  it  is  therefore  still 
doubtful  whether  fertilization  really  takes  place.  Shortly  after  these 
organs  are  full-grown,  several  short  branches  grow  up  about  them,  and 
soon  completely  envelop  them  (l>,  E).  These  branches  soon  grow  to- 
gether, and  cross-walls  are  formed  in  them,  so  that  the  young  spore  fruit 

1  The  filaments  are  attached  to  the  surface  of  the  leaf  by  suckers, 
which  are  not  so  readily  seen  in  this  species  as  in  some  others.  A  mildew 
growing  abundantly  in  autumn  on  the  garden  chrysanthemum,  however, 
shows  them  very  satisfactorily  if  a  bit  of  the  epidermis  of  a  leaf  on  which 
the  fungus  is  just  beginning  to  grow  is  sliced  off  with  a  sharp  razor  and 
mounted  in  dilute  glycerine,  or  water,  removing  the  air  with  alcohol. 
These  suckers  are  then  seen  to  be  globular  bodies,  penetrating  the  outer 
wall  of  the  cell  (Fig.  40). 


FUNGI. 


69 


appears  surrounded  by  a  single  layer  of  cells,  sufficiently  transparent, 
however,  to  allow  a  view  of  the  interior. 

The  antheridiuni  undergoes  no  further  change,  but  the  archicarp  soon 
divides  into  two  cells,  —  a  small  basal  one  and  a  larger  upper  cell.  There 
next  grow  from  the  inner  surface  of  the  covering  cells,  short  filaments, 
that  almost  completely  fill  the  space  between  the  archicarp  and  the  wall. 
An  optical  section  of  such  a  stage  (Fig.  39,  F)  shows  a  double  wall  and 
the  two  cells  of  the  archicarp.  The  spore  fruit  now  enlarges  rapidly,  and 
the  outer  cells  become  first  yellow  and  then  dark  brown,  the  walls  becom- 
ing thicker  and  harder  as  they  change  color.  Sometimes  special  filaments 
or  appendages  grow  out  from  their  outer  surfaces,  and  these  are  also  dark- 


FIG.  41.  —  Forms  of  mildews  (Erysiphe).  A,  Microsphsera,  a  spore  fruit,  x  150. 
B,  cluster  of  spore  sacs  of  the  same,  x  150.  (7,  a  single  appendage,  x  300. 
D,  end  of  an  appendage  of  Uncinula,  x  300.  E,  appendage  of  Phyllactinia, 
x  150. 

colored.  Shortly  before  the  fruit  is  ripe,  the  upper  cell  of  the  archicarp, 
which  has  increased  many  times  in  size,  shows  a  division  of  its  contents 
into  eight  parts,  each  of  which  develops  a  wall  and  becomes  an  oval  spore. 
By  crushing  the  ripe  spore  fruit,  these  spores  still  enclosed  in  the  mother 
cell  (ascus)  may  be  forced  out  (Fig.  39,  H).  These  spores  do  not  germi- 
nate at  once,  but  remain  dormant  until  the  next  year. 

Frequently  other  structures,  resembling  somewhat  the  spore  fruits,  are 
found  associated  with  them  (Fig.  39,  /,  A'),  and  were  for  a  long  time  sup- 
posed to  be  a  special  form  of  reproductive  organ  ;  but  they  are  now  known 
to  belong  to  another  fungus  (Cicinnobulus),  parasitic  upon  the  mildew. 
They  usually  appear  at  the  base  of  the  chains  of  conidia,  causing  the  basal 
cell  to  enlarge  to  many  times  its  original  size,  and  finally  kill  the  young 


70 


BOTANY. 


conidia,  which  shrivel  up.  A  careful  examination  reveals  the  presence  of 
very  fine  filaments  within  those  of  the  mildew,  which  may  be  traced  up  to 
the  base  of  the  conidial  branch,  where  the  receptacle  of  the  parasite  is 
forming.  The  spores  contained  in  these  receptacles  are  very  small  (Fig. 
39,  K),  and  when  ripe  exude  hi  long,  worm- shaped  masses,  if  the  recep- 
tacle is  placed  in  water. 

The  mildews  may  be  divided 
into  two  genera:  Podosphcera, 
with  a  single  ascus  in  the  spore 
fruit;  and  Erysiplie,  with  two 
or  more.  In  the  latter  the 
archicarp  branches,  each  branch 
bearing  a  spore  sac  (Fig.  41,  B) . 

The  appendages  growing  out 
from  the  wall  of  the  spore  fruit 
are  often  very  beautiful  in 
form,  and  the  two  genera  given 
above  are  often  subdivided  ac- 
cording to  the  form  of  these 
appendages. 

A  common  mould  closely 
allied  to  the  mildews  is  found 
on  various  articles  of  food  when 
allowed  to  remain  damp,  and  is 
also  very  common  on  botani- 
cal specimens  that  have  been 
poorly  dried,  and  hence  is  often 
called  "  herbarium  mould  "  (Eu- 
rotium  herbariorum) . 


FIG.  42.—  A,  spore  bearing  filament 
of  the  herbarium  mould  (Euro- 
tium),  x  150.  B,  C,  another  species 
showing  the  way  in  which  the 
spores  are  borne  —  optical  section 
—  x  150.  D,  spore  fruit  of  the 
herbarium  mould,  x  150.  E,  spore 
sac.  F,  spores,  x  300.  G,  spore- 
bearing  filament  of  the  common 
blue  mould  (PenicilUum),  x  300. 
sp.  the  spores. 


The  conidia  are  of  a  greenish  color,  and  produced  on  the  ends  of  upright 
branches  which  are  enlarged  at  the  end,  and  from  which  grow  out  little 
prominences,  which  give  rise  to  the  conidia  in  the  same  way  as  we  have 
seen  in  the  mildews  (Fig.  42,  A). 

Spore  fruits  much  like  those  of  the  mildews  are  formed  later,  and  are 
visible  to  the  naked  eye  as  little  yellow  grains  (Fig.  42,  D}.  These  con- 
tain numerous  very  small  spore  sacs  (E),  each  with  eight  spores. 


FUNGI.  71 

There  are  numerous  common  species  of  Eurotium,  differing 
in  color  and  size,  some  being  yellow  or  black,  and  larger  than 
the  ordinary  green  form. 

Another  form,  common  everywhere  on  mouldy  food  of  all 
kinds,  as  well  as  in  other  situations,  is  the  blue  mould  (Peni- 
cillium).  This,  in  general  appearance,  resembles  almost  exactly 
the  herbarium  mould,  but  is  immediately  distinguishable  by  a 
microscopic  examination  (Fig.  42,  6r). 

In  studying  all  of  these  forms,  they  may  be  mounted,  as  directed  for 
the  black  moulds,  in  dilute  glycerine  ;  but  must  be  handled  with  great  care, 
as  the  spores  become  shaken  off  with  the  slightest  jar. 

Of  the  larger  Ascomycetes,  the  cup  fungi  (Discomycetes)  may 
be  taken  as  types.  The  spore  fruit  in  these  forms  is  often  of 
considerable  size,  and,  as  their  name  indicates,  is  open,  having 
the  form  of  a  flat  disc  or  cup.  A  brief  description  of  a  com- 
mon one  will  suffice  to  give  an  idea  of  their  structure  and 
development. 

Ascobolus  (Fig.  43)  is  a  small,  disc-shaped  fungus,  growing 
on  horse  dung.  By  keeping  some  of  this  covered  with  a  bell 
jar  for  a  week  or  two,  so  as  to  retain  the  moisture,  at  the  end 
of  this  time  a  large  crop  of  the  fungus  will  probably  have 
made  its  appearance.  The  part  visible  is  the  spore  fruit  (Fig. 
43,  A),  of  a  light  brownish  color,  and  about  as  big  as  a  pin- 
head. 

Its  development  may  be  readily  followed  by  teasing  out  in  water  the 
youngest  specimens  that  can  be  found,  taking  care  to  take  up  a  little  of 
the  substratum  with  it,  as  the  earliest  stages  are  too  small  to  be  visible  to 
the  naked  eye.  The  spore  fruits  arise  from  filaments  not  unlike  those  of 
the  mildews,  and  are  preceded  by  the  formation  of  an  archicarp  composed 
of  several  cells,  and  readily  seen  through  the  walls  of  the  young  fruit 
(Fig.  43,  B).  In  the  study  of  the  early  stages,  a  potash  solution  will  be 
found  useful  in  rendering  them  transparent. 

The  young  fruit  has  much  the  same  structure  as  that  of  the  mildews, 
but  the  spore  sacs  are  much  more  numerous,  and  there  are  special  sterile 
filaments  developed  between  them.  If  the  young  spore  fruit  is  treated 
with  chlor-iodide  of  zinc,  it  is  rendered  quite  transparent,  and  the  young 


72 


BOTANY. 


spore  sacs  colored  a  beautiful  blue,  so  that  they  are  readily  distinguish- 
able. 

The  development  of  the  spore  sacs  may  be  traced  by  carefully  crushing 
the  young  spore  fruits  in  water.  The  young  spore  sacs  (Fig.  43,  E  i)  are  col- 
orless, with  granular  protoplasm,  in  which  a  nucleus  can  often  be  easily 
seen.  The  nucleus  subsequently  divides  repeatedly,  until  there  are  eight 
nuclei,  about  which  the  protoplasm  collects  to  form  as  many  oval  masses, 
each  of  which  develops  a  wall  and  becomes  a  spore  (Figs.  u-iv).  These 


FIG.  43.—  A,  a  small  cup  fungus  (Ascobolus) ,  x  5.  B,  young  spore  fruit,  x  300. 
ar.  archicarp.  C,  an  older  one,  x  150.  ar.  archicarp.  sp.  young  spore  sacs. 
D,  section  through  a  full-grown  spore  fruit  (partly  diagrammatic) ,  x  25.  sp. 
spore  sacs.  E,  development  of  spore  sacs  and  spores:  i-in,  x  300;  iv, 
x  150.  F,  ripe  spores.  G,  a  sterile  filament  (paraphysis) ,  x  300.  H,  large 
scarlet  cup  fungus  (Peziza) ,  natural  size. 

are  imbedded  in  protoplasm,  which  is  at  first  granular,  but  afterwards 
becomes  almost  transparent.  As  the  spores  ripen,  the  wall  acquires  a 
beautiful  violet-purple  color,  changing  later  to  a  dark  purple- brown,  and 
marked  with  irregular  longitudinal  ridges  (Fig.  43,  F).  The  full-grown 
spore  sacs  (Fig.  43,  E,  W)  are  oblong  in  shape,  and  attached  by  a  short 
stalk.  The  sterile  filaments  between  them  often  become  curiously  en- 
larged at  the  end  (G).  As  the  spore  fruit  ripens,  it  opens  at  the  top,  and 


FUNGI.  73 

spreads  out  so  as  to  expose  the  spore  sacs  as  they  discharge  their  con- 
tents (Fig.  43,  D). 

Of  the  larger  cup  fungi,  those  belonging  to  the  genus  Peziza 
(Fig.  43,  H)  are  common,  growing  on  bits  of  rotten  wood  on 
the  ground  in  woods.  They  are  sometimes  bright  scarlet  or 
orange-red,  and  very  showy.  Another  curious  form  is  the 
morel  (Morchella),  common  in  the  spring  in  dry  woods.  It  is 
stalked  like  a  mushroom,  but  the  surface  of  the  conical  cap  is 
honeycombed  with  shallow  depressions,  lined  with  the  spore 
sacs. 

ORDER  Lichenes. 

Under  the  name  of  lichens  are  comprised  a  large  number  of 
fungi,  differing  a  good  deal  in  structure,  but  most  of  them  not 
unlike  the  cup  fungi.  They  are,  with  few  exceptions,  parasitic 
upon  various  forms  of  algae,  with  which  they  are  so  intimately 
associated  as  to  form  apparently  a  single  plant.  They  grow 
everywhere  on  exposed  rocks,  on  the  ground,  trunks  of  trees, 
fences,  etc.,  and  are  found  pretty  much  the  world  over.  Among 
the  commonest  of  plants  are  the  lichens  of  the  genus  Parmelia 
(Fig.  44,  A),  growing  everywhere  011  tree  trunks,  wooden 
fences,  etc.,  forming  gray,  flattened  expansions,  with  much 
indented  and  curled  margins.  When  dry,  the  plant  is  quite 
brittle,  but  on  moistening  becomes  flexible,  and  at  the  same 
time  more  or  less  decidedly  green  in  color.  The  lower 
surface  is  white  or  brown,  and  often  develops  root-like  proc- 
esses by  which  it  is  fastened  to  the  substratum.  Some- 
times small  fragments  of  the  plant  become  detached  in  such 
numbers  as  to  form  a  grayish  powder  over  certain  portions  of 
it.  These,  when  supplied  with  sufficient  moisture,  will  quickly 
produce  new  individuals. 

Not  infrequently  the  spore  fruits  are  to  be  met  with  flat 
discs  of  a  reddish  brown  color,  two  or  three  millimetres  in 
diameter,  and  closely  resembling  a  small  cup  fungus.  They 


74 


BOTANY. 


Ji 


are  at  first  almost  closed,  but  expand  as  they  mature  (Fig.  44, 
A,  ap.). 

If  a  thin  vertical  section  of  the  plant  is  made  and  sufficiently  magnified, 
it  is  found  to  be  made  up  of  somewhat  irregular,  thick- walled,  colorless 
filaments,  divided  by  cross- walls  as  in  the  other  sac-fungi.  In  the  central 
parts  of  the  plant  these  are  rather  loose,  but  toward  the  outside  become 
very  closely  interwoven  and  often  grown  together,  so  as  to  form  a  tough 

rind.  Among  the  filaments 
of  the  outer  portion  are  nu- 
merous small  green  cells, 
that  closer  examination 
shows  to  be  individuals  of 
Protococcus,  or  some  simi- 
lar green  algee,  upon  which 
the  lichen  is  parasitic. 
These  are  sufficiently  abun- 
dant to  form  a  green  line 
just  inside  the  rind  if  the 
section  is  examined  with  a 
simple  lens  (Fig.  44,  B). 

The  spore  fruits  of  the 
lichens  resemble  in  all  es- 
sential respects  those  of 
the  cup  fungi,  and  the  spore 
sacs  (Fig.  44,  F)  are  much 
the  same,  usually,  though 
not  always,  containing  eight 
spores,  which  are  some- 
times two-celled.  The  ster- 
ile filaments  between  the 
spore  sacs  usually  have 

D,  a  spermagonium  of  "Collema,  x  25.    E,  a      thickened  ends,  which  are 
single  Nostoc  thread.  F,  spore  sacs  andpara- 
physes  of  Usnea,  x  300.    G,  Protococcus  cells 
and  fungus  filaments  of  Usnea. 


FIG.  44.—  A,  a  common  lichen  (Parmelia),  of 
the  natural  size.  ap.  spore  fruit.  B,  section 
through  one  of  the  spore  fruits,  x  5.  C,  sec- 
tion through  the  body  of  a  gelatinous  lichen 
(Collema),  showing  the  Nostoc  individuals 
surrounded  by  the  fungus  filaments,  x  300. 


dark-colored,  and  give  the 
color  to  the  inner  surface 
of  the  spore  fruit. 

In  Figure  45,  H,  is  shown  one  of  the  so-called  "  Soredia," l  a  group  of 
the  algae,  upon  which  the  lichen  is  parasitic,  surrounded  by  some  of  the 


Sing,  soredium. 


FUNGI. 


75 


filaments,  the  whole  separating  spontaneously  from  the  plant  and  giving 
rise  to  a  new  one. 

Owing  to  the  toughness  of  the  filaments,  the  finer  structure 
of  the  lichens  is  often  difficult  to  study,  and  free  use  of  caustic 
potash  is  necessary  to  soften  and  make  them  manageable. 

According  to  their  form,  lichens  are  sometimes  divided  into 


FIG.  45.  —  Forms  of  lichens.  A,  a  branch  with  lichens  growing  upon  it,  one- 
half  natural  size.  B,  Usnea,  natural  size.  ap.  spore  fruit.  C,  Sticta,  one- 
half  natural  size.  D,  Peltigera,  one-half  natural  size.  ap.  spore  fruit.  E,  a 
single  spore  fruit,  x  2.  F,  Cladonia,  natural  size.  G,  a  piece  of  bark  from 
a  beech,  with  a  crustaceous  lichen  (Graphis)  growing  upon  it,  x  2.  ap.  spore 
fruit.  H,  Soredium  of  a  lichen,  x  300. 

the  bushy  (f ruticose),  leafy  (frondose),  incrusting  (crustaceous), 
and  gelatinous.  Of  the  first,  the  long  gray  Usnea  (Fig.  45, 
A,  B),  which  drapes  the  branches  of  trees  in  swamps,  is  a 
familiar  example ;  of  the  second,  Parmelia,  Sticta  (Fig.  45,  O) 
and  Peltigera  (D)  are  types  ;  of  the  third,  Graphis  (G),  common 
on  the  trunks  of  beech-trees,  to  which  it  closely  adheres ;  and 


76 


BOTANY. 


of  the  last,  Collema  (Fig.  44,  C,  D,  E),  a  dark  greenish,  gelat- 
inous form,  growing  on  mossy  tree  trunks,  and  looking  like  a 
colony  of  Nostoc,  which  indeed  it  is,  but  differing  from  an  ordi- 
nary colony  in  being  penetrated  everywhere  by  the  filaments  of 
the  fungus  growing  upon  it. 

Not  infrequently  in  this  form,  as  well  as  in  other  lichens,  special  cavities, 
known  as  sperm ogonia  (Fig.  44,  JD),  are  found,  in  which  excessively  small 
spores  are  produced,  which  have  been  claimed  to  be  male  reproductive 
cells,  but  the  latest  investigations  do  not  support  this  theory. 

The  last  group  of  the  Ascomy- 
cetes  are  the  "black  fungi,"  Pyre- 
nomycetes,  represented  by  the  black 
knot  of  cherry  and  plum  trees, 
shown  in  Figure  46.  They  are 
mainly  distinguished  from  the  cup 
fungi  by  producing  their  spore  sacs 
in  closed  cavities.  Some  are  para- 
sites ;  others  live  on  dead  wood, 
leaves,  etc.,  forming  very  hard 
masses,  generally  black  in  color, 
giving  them  their  common  name. 
Owing  to  the  hardness  of  the 
masses,  they  are  very  difficult  to 
manipulate ;  and,  as  the  structure  is  not  essentially  different 
from  that  of  the  Discomycetes,  the  details  will  not  be  entered 
into  here. 

Of  the  parasitic  forms,  one  of  the  best  known  is  the  u  ergot  " 
of  rye,  more  or  less  used  in  medicine.  Other  forms  are  known 
that  attack  insects,  particularly  caterpillars,  which  are  killed 
by  their  attacks. 


FIG.  46.  —  Branch  of  a  plum- 
tree  attacked  by  black  knot. 
Natural  size. 


CHAPTER   X. 

FUNGI  —  Continued. 
CLASS  Basidiomycetes. 

THE  Basidiomycetes  include  the  largest  and  most  highly 
developed  of  the  fungi,  among  which  are  many  familiar  forms, 
such  as  the  mushrooms,  toadstools,  puff-balls,  etc.  Besides 
these  large  and  familiar  forms,  there  are  other  simpler  and 
smaller  ones  that,  according  to  the  latest  investigations,  are 
probably  related  to  them,  though  formerly  regarded  as  con- 
stituting a  distinct  group.  The  most  generally  known  of  these 
lower  Basidiomycetes  are  the  so-called  rusts.  The  larger  Ba- 
sidiomycetes are  for  the  most  part  saprophytes,  living  in  decay- 
ing vegetable  matter,  but  a  few  are  true  parasites  upon  trees 
and  others  of  the  flowering  plants. 

All  of  the  group  are  characterized  by  the  production  of 
spores  at  the  top  of  special  cells  known  as  basidia,1  the  number 
produced  upon  a  single  basidium  varying  from  a  single  one  to 
several. 

Of  the  lower  Basidiomycetes,  the  rusts  (Uredinece)  offer  com- 
mon and  easily  procurable  forms  for  study.  They  are  exclu- 
sively parasitic  in  their  habits,  growing  within  the  tissues  of 
the  higher  land  plants,  which  they  often  injure  seriously. 
They  receive  their  popular  name  from  the  reddish  color  of  the 
masses  of  spores  that,  when  ripe,  burst  through  the  epidermis 
of  the  host  plant.  Like  many  other  fungi,  the  rusts  have  several 
kinds  of  spores,  which  are  often  produced  on  different  hosts ; 
thus  one  kind  of  wheat  rust  lives  during  part  of  its  life  within 

1  Sing,  basidium. 

77 


78 


BOTANY. 


the  leaves  of  the  barberry,  where  it  produces  spores  quite  dif- 
ferent from  those  upon  the  wheat ;  the  cedar  rust,  in  the  same 
way,  is  found  at  one  time  attacking  the  leaves  of  the  wild  crab- 
apple  and  thorn. 


FIG.  47.  —  A,  a  branch  of  red  cedar  attacked  by  a  rust  (Gymnosporangium), 
causing  a  so-called  "cedar  apple,"  x  £.  B,  spores  of  'the  same,  one  be- 
ginning to  germinate,  x  300.  C,  a  spore  that  has  germinated,  each  cell 
producing  a  short,  divided  filament  (basidium),  which  in  turn  gives  rise  to 
secondary  spores  (sp.),  x  300.  J),  part  of  the  leaf  of  a  hawthorn  attacked  by  the 
cluster  cup  stage  of  the  same  fungus,  upper  side  showing  spermogonia,  natural 
size.  E,  cluster  cups  (Roestelia)  of  the  same  fungus,  natural  size.  F,  tip  of 
a  leaf  of  the  Indian  turnip  (A rixsema),  bearing  the  cluster  cup  (jfScidivm) 
stage  of  a  rust,  x  2.  G,  vertical  section  through  a  young  cluster  cup.  H, 
similar  section  through  a  mature  one,  x  50.  /,  germinating  spores  of  //, 
x  300.  J,  part  of  a  corn  leaf,  with  black  rust,  natural  size.  K,  red  rust  spore 
of  the  wheat  rust  (Puccinia  yraminis),  x  300.  L,  forms  of  black-rust  spores  : 
I,  Uromyces  ;  n,  Puccinia  ;  in,  Phraymidiwm. 

The  first  form  met  with  in  most  rusts  is  sometimes  called 
the  "cluster-cup"  stage,  and  in  many  species  is  the  only 
stage  known.  In  Figure  47,  F,  is  shown  a  bit  of  the  leaf  of 
the  Indian  turnip  (Ariscemd)  affected  by  one  of  these  "cluster- 
cup  "  forms.  To  the  naked  eye,  or  when  slightly  magnified, 


FUNGI.  79 

the  masses  of  spores  appear  as  bright  orange  spots,  mostly 
upon  the  lower  surface.  The  affected  leaves  are  more  or  less 
checked  in  their  growth,  and  the  upper  surface  shows  lighter 
blotches,  corresponding  to  the  areas  below  that  bear  the  cluster 
cups.  These  at  first  appear  as  little  elevations  of  a  yellowish 
color,  and  covered  with  the  epidermis  ;  but  as  the  spores  ripen 
they  break  through  the  epidermis,  which  is  turned  back  around 
the  opening,  the  whole  forming  a  little  cup  filled  with  a  bright 
orange  red  powder,  composed  of  the  loose  masses  of  spores. 

Putting  a  piece  of  the  affected  leaf  between  two  pieces  of  pith  so  as  to 
hold  it  firmly,  with  a  little  care  thin  vertical  sections  of  the  leaf,  including 
one  of  the  cups,  may  be  made,  and  mounted,  either  in  water  or  glycerine, 
removing  the  air  with  alcohol.  We  find  that  the  leaf  is  thickened  at  this 
point  owing  to  a  diseased  growth  of  the  cells  of  the  leaf,  induced  by  the 
action  of  the  fungus.  The  mass  of  spores  (Fig.  47,  G)  is  surrounded  by  a 
closely  woven  mass  of  filaments,  forming  a  nearly  globular  cavity.  Occupy- 
ing the  bottom  of  the  cup  are  closely  set,  upright  filaments,  each  bearing 
a  row  of  spores,  arranged  like  those  of  the  white  rusts,  but  so  closely 
crowded  as  to  be  flattened  at  the  sides.  The  outer  rows  have  thickened 
walls,  and  are  grown  together  so  as  to  form  the  wall  of  the  cup. 

The  spores  are  filled  with  granular  protoplasm,  in  which  are  numerous 
drops  of  orange-yellow  oil,  to  which  is  principally  due  their  color.  As 
the  spores  grow,  they  finally  break  the  overlying  epidermis,  and  then  be- 
come rounded  as  the  pressure  from  the  sides  is  relieved.  They  germinate 
within  a  few  hours  if  placed  in  water,  sending  out  a  tube,  into  which 
pass  the  contents  of  the  spore  (Fig.  47,  /). 

One  of  the  most  noticeable  of  the  rusts  is  the  cedar  rust 
(Gymnosporangium) ,  forming  the  growths  known  as  "cedar 
apples,"  often  met  with  on  the  red  cedar.  These  are  rounded 
masses,  sometimes  as  large  as  a  walnut,  growing  upon  the 
small  twigs  of  the  cedar  (Fig.  47,  A) .  This  is  a  morbid  growth 
of  the  same  nature  as  those  produced  by  the  white  rusts  and 
smuts.  If  one  of  these  cedar  apples  is  examined  in  the  late 
autumn  or  winter,  it  will  be  found  to  have  the  surface  dotted 
with  little  elevations  covered  by  the  epidermis,  and  on  remov- 
ing this  we  find  masses  of  forming  spores.  These  rupture  the 


80  BOTANY. 

epidermis  early  in  the  spring,  and  appear  then  as  little  spikes 
of  a  rusty  red  color.  If  they  are  kept  wet  for  a  few  hours, 
they  enlarge  rapidly  by  the  absorption  of  water,  and  may  reach 
a  length  of  four  or  five  centimetres,  becoming  gelatinous  in 
consistence,  and  sometimes  almost  entirely  hiding  the  surface 
of  the  "apple."  In  this  stage  the  fungus  is  extremely  con- 
spicuous, and  may  frequently  be  met  with  after  rainy  weather 
in  the  spring. 

This  orange  jelly,  as  shown  by  the  microscope,  is  made  up  of  elongated 
two-celled  spores  (teleuto  spores),  attached  to  long  gelatinous  stalks  (Fig. 
47,  _B).  They  are  thick-walled,  and  the  contents  resemble  those  of  the 
cluster-cup  spores  described  above. 

To  study  the  earlier  stages  of  germination  it  is  best  to  choose  specimens 
in  which  the  masses  of  spores  have  not  been  moistened.  By  thoroughly 
wetting  these,  and  keeping  moist,  the  process  of  germination  may  be 
readily  followed.  Many  usually  begin  to  grow  within  twenty- four  hours 
or  less.  Each  cell  of  the  spore  sends  out  a  tube  (Fig.  47,  (7),  through  an 
opening  in  the  outer  wall,  and  this  tube  rapidly  elongates,  the  spore  con- 
tents passing  into  it,  until  a  short  filament  (basidium)  is  formed,  which 
then  divides  into  several  short  cells.  Each  cell  develops  next  a  short, 
pointed  process,  which  swells  up  at  the  end,  gradually  taking  up  all  the 
contents  of  the  cell,  until  a  large  oval  spore  (sp.)  is  formed  at  the  tip, 
containing  all  the  protoplasm  of  the  cell. 

Experiments  have  been  made  showing  that  these  spores  do 
not  germinate  upon  the  cedar,  but  upon  the  hawthorn  or  crab- 
apple,  where  they  produce  the  cluster-cup  stage  often  met  with 
late  in  the  summer.  The  affected  leaves  show  bright  orange- 
yellow  spots  about  a  centimetre  in  diameter  (Fig.  47,  D),  and 
considerably  thicker  than  the  other  parts  of  the  leaf.  On  the 
upper  side  of  these  spots  may  be  seen  little  black  specks,  which 
microscopic  examination  shows  to  be  spermogonia,  resembling 
those  of  the  lichens.  Later,  on  the  lower  surface,  appear  the 
cluster  cups,  whose  walls  are  prolonged  so  that  they  form  little 
tubular  processes  of  considerable  length  (Fig.  47,  E). 

In  most  rusts  the  teleuto  spores  are  produced  late  in  the  summer  or 
autumn,  and  remain  until  the  following  spring  before  they  germinate. 


FUNGI.  81 

They  are  very  thick-walled,  the  walls  being  dark-colored,  so  that  in  mass 
they  appear  black,  and  constitute  the  "black- rust"  stage  (Fig.  47,  J). 
Associated  with  these,  but  formed  earlier,  and  germinating  immediately, 
are  often  to  be  found  large  single-celled  spores,  borne  on  long  stalks. 
They  are  usually  oval  in  form,  rather  thin-walled,  but  the  outer  surface 
sometimes  provided  with  little  points.  The  contents  are  reddish,  so  that 
in  mass  they  appear  of  the  color  of  iron  rust,  and  cause  the  "  red  rust "  of 
wheat  and  other  plants,  upon  which  they  are  growing. 

The  classification  of  the  rusts  is  based  mainly  upon  the  size 
and  shape  of  the  teleuto  spores  where  they  are  known,  as  the 
cluster-cup  and  red-rust  stages  are  pretty  much  the  same  in 
all.  Of  the  commoner  genera  Melampsora  and  Uromyces  (Fig. 
47,  L  i),  have  unicellular  teleuto  spores  ;  Puccinia  (n)  and 
Gymnosporangium,  two-celled  spores ;  Triphragmium,  three- 
celled;  and  Phragmidium  (in),  four  or  more. 

The  rusts  are  so  abundant  that  a  little  search  can  scarcely 
fail  to  find  some  or  all  of  the  stages.  The  cluster-cup  stages 
are  best  examined  fresh,  or  from  alcoholic  material ;  the  teleuto 
spores  may  be  dried  without  affecting  them. 

Probably  the  best-known  member  of  the  group  is  the  wheat 
rust  (Puccinia  gmminis),  which  causes  so  much  damage  to 
wheat  and  sometimes  to  other  grains.  The  red-rust  stage  may 
be  found  in  early  summer  ;  the  black-rust  spores  in  the  stubble 
and  dead  leaves  in  the  autumn  or  spring,  forming  black  lines 
rupturing  the  epidermis. 

Probably  to  be  associated  with  the  lower  Basidiomycetes  are 
the  large  fungi  of  which  Tremella  (Fig.  51,  A)  is  an  example. 
They  are  jelly-like  forms,  horny  and  somewhat  brittle  when 
dry,  but  becoming  soft  when  moistened.  They  are  common, 
growing  on  dead  twigs,  logs,  etc.,  and  are  usually  brown  or 
orange-yellow  in  color. 

Of  the  higher  Basidiomycetes,  the  toadstools,  mushrooms, 
etc.,  are  the  highest,  and  any  common  form  will  serve  for  study. 
One  of  the  most  accessible  and  easily  studied  forms  is  Coprinus, 
of  which  there  are  several  species  growing  on  the  excrement  of 
various  herbivorous  animals.  They  not  infrequently  appear  on 


82 


BOTANY. 


horse  manure  that  has  been  kept  covered  with  a  glass  for  some 
time,  as  described  for  Ascobolus.  After  two  or  three  weeks 
some  of  these  fungi  are  very  likely  to  make  their  appearance, 
and  new  ones  continue  to  develop  for  a  long  time. 

The  first  trace  of  the  plant,  visible  to  the  naked  eye,  is  a 
little  downy,  white  speck,  just  large  enough  to  be  seen.  This 
rapidly  increases  in  size,  becoming  oblong  in  shape,  and  growing 
B 


FIG.  48.  —  A,  young.  B,  full-grown  fruit  of  a  toadstool  (Coprinus),  x  2.  C, 
under  side  of  the  cap,  showing  the  radiating  "  gills,"  or  spore-bearing  plates. 
D,  section  across  one  of  the  young  gills,  x  150.  E,  F,  portions  of  gills  from 
a  nearly  ripe  fruit,  x  300.  sp.  spores,  x,  sterile  cell.  In  F,  a  basidium  is 
shown,  with  the  young  spores  just  forming.  G,  H,  young  fruits,  x  50. 

finally  somewhat  darker  in  color ;  and  by  the  time  it  reaches 
a  height  of  a  few  millimetres  a  short  stalk  becomes  percept- 
ible, and  presently  the  whole  assumes  the  form  of  a  closed 
umbrella.  The  top  is  covered  with  little  prominences,  that 
diminish  in  number  and  size  toward  the  bottom.  After  the 
cap  reaches  its  full  size,  the  stalk  begins  to  grow,  slowly  at 
first,  but  finally  with  great  rapidity,  reaching  a  height  of 


FUNGI.  83 

several  centimetres  within  a  few  hours.  At  the  same  time 
that  the  stalk  is  elongating,  the  cap  spreads  out,  radial  clefts 
appearing  on  its  upper  surface,  which  flatten  out  very  much  as 
the  folds  of  an  umbrella  are  stretched  as  it  opens,  and  the 
spaces  between  the  clefts  appear  as  ridges,  comparable  to  the 
ribs  of  the  umbrella  (Fig.  48,  B).  The  under  side  of  the  cap 
has  a  number  of  ridges  running  from  the  centre  to  the  margin, 
and  of  a  black  color,  due  to  the  innumerable  spores  covering 
their  surface  (C).  Almost  as  soon  as  the  umbrella  opens,  the 
spores  are  shed,  and  the  whole  structure  shrivels  up  and  dis- 
solves, leaving  almost  no  trace  behind. 

If  we  examine  microscopically  the  youngest  specimens  procurable,  free- 
ing from  air  with  alcohol,  and  mounting  in  water  or  dilute  glycerine,  we 
find  it  to  be  a  little,  nearly  globular  mass  of  colorless  filaments,  with 
numerous  cross-walls,  the  whole  arising  from  similar  looser  filaments 
imbedded  in  the  substratum  (Fig.  48,  G).  If  the  specimen  is  not  too  young, 
a  denser  central  portion  can  be  made  out,  and  in  still  older  ones  (Fig.  48, 
H)  this  central  mass  has  assumed  the  form  of  a  short,  thick  stalk,  crowned 
by  a  flat  cap,  the  whole  invested  by  a  loose  mass  of  filaments  that  merge 
more  or  less  gradually  into  the  central  portion.  By  the  time  the  spore 
fruit  (for  this  structure  corresponds  to  the  spore  fruit  of  the  Ascomycetes) 
reaches  a  height  of  two  or  three  millimetres,  and  is  plainly  visible  to  the 
naked  eye,  the  cap  grows  downward  at  the  margins,  so  as  to  almost  en- 
tirely conceal  the  stalk.  A  longitudinal  section  of  such  a  stage  shows  the 
stalk  to  be  composed  of  a  small-celled,  close  tissue  becoming  looser  in 
the  cap,  on  whose  inner  surface  the  spore-bearing  ridges  ("gills"  or 
Lamellw)  have  begun  to  develop.  Some  of  these  run  completely  to  the 
edge  of  the  cap,  others  only  part  way.  To  study  their  structure,  make 
cross-sections  of  the  cap  of  a  nearly  full-grown,  but  unopened,  specimen, 
and  this  will  give  numerous  sections  of  the  young  gills.  We  find  them  to 
be  flat  plates,  composed  within  of  loosely  interwoven  filaments,  whose 
ends  stand  out  at  right  angles  to  the  surface  of  the  gills,  forming  a  layer 
of  closely-set  upright  cells  (basidia)  (Fig.  48,  D).  These  are  at  first  all 
alike,  but  later  some  of  them  become  club-shaped,  and  develop  at  the  end 
several  (usually  four)  little  points,  at  the  end  of  which  spores  are  formed 
in  exactly  the  same  way  as  we  saw  in  the  germinating  teleuto  spores  of 
the  cedar  rust,  all  the  protoplasm  of  the  basidium  passing  into  the  grow- 
ing spores  (Fig.  48,  E,  F).  The  ripe  spores  (E,  sp.)  are  oval,  and  possess 
a  firm,  dark  outer  wall.  Occasionally  some  of  the  basidia  develop  into 


84 


BOTANY. 


very  large  sterile  cells  (E,  x),  projecting  far  beyond  the  others,  and  often 
reaching  the  neighboring  gill. 

Similar  in  structure  and  development  to  Coprinus  are  all  the 
large  and  common  forms  ;  but  they  differ  much  in  the  position 
of  the  spore-bearing  tissue,  as  well  as  in  the  form  and  size  of 
the  whole  spore  fruit.  They  are  sometimes  divided,  according 
to  the  position  of  the  spores,  into  three  orders :  the  closed- 
fruited  (Angiocarpous)  forms,  the  half- 
closed  (Hemi-angiocarpous) ,  and  the 
open  or  naked-fruited  forms  (Gymno- 
carpous). 

Of  the  first,  the  puff-balls  (Fig.  49) 
are  common  examples.     One  species, 


FIG.  49.  —  Basidiomycetes. 

A,  common     puff-ball 
(Ly coper dori).    B,  earth 
star   (Geaster).    A,  x  £. 

B,  one-half  natural  size. 


FIG.  50.  —  Birds'-nest  fungus  (Cyathus). 
A,  young.  B,  full  grown.  C,  section 
through  B,  showing  the  "  sporangia  " 
(sp.).  All  twice  the  natural  size. 


the  giant  puff-ball  (Lycoperdon  giganteum),  often  reaches  a 
diameter  of  thirty  to  forty  centimetres.  The  earth  stars 
(Geaster)  have  a  double  covering  to  the  spore  fruit,  the 
outer  one  splitting  at  maturity  into  strips  (Fig.  49,  .  B) . 
Another  pretty  and  common  form  is  the  little  birds'-nest 
fungus  (Cyathus),  growing  on  rotten  wood  or  soil  containing 
much  decaying  vegetable  matter  (Fig.  50). 

In  the  second  order  the  spores  are  at  first  protected,  as  we 
have  seen  in  Coprinus,  which  belongs  to  this  order,  but  finally 


FUNGI. 


85 


become  exposed.  Here  belong  the  toadstools  and  mushrooms 
(Fig.  51,  -B),  the  large  shelf-shaped  fungi  (Potyporus),  so  com- 
mon on  tree  trunks  and  rotten  logs  (Fig.  51,  (/,'  D,  E)}  and  the 
prickly  fungus  (Hydnum)  (Fig.  51,  G). 


FIG.  51.  —  Forms  of  Basidiomycetes.  A,  Tremella,  one-half  natural  size.  B, 
Agaricus,  natural  size.  C,  E,  Polyporus  :  C,  x  % ;  E,  x  y4.  Z),  part  of  the 
under  surface  of  D,  natural  size.  F,  Clavaria,  a  small  piece,  natural  size. 
G,  Hydnum,  a  piece  of  the  natural  size. 

Of  the  last,  or  naked-fruited  forms,  the  commonest  belong 
to  the  genus  Clavaria  (Fig.  51,  F),  smooth-branching  forms, 
usually  of  a  brownish  color,  bearing  the  spores  directly  upon 
the  surface  of  the  branches. 


CHAPTER   XL 


SUB-KINGDOM   IV. 
BRYOPHYTA. 

THE  Bryophytes,  or  mosses,  are  for  the  most  part  land  plants, 
though  a  few  are  aquatic,  and  with  very  few  exceptions  are 
richly  supplied  with  chlorophyll.  They  are  for  the  most  part 
small  plants,  few  of  them  being  over  a  few  centimetres  in 
height ;  but,  nevertheless,  compared  with  the  plants  that  we 
have  heretofore  studied,  quite  complex  in  their  structure.  The 
lowest  members  of  the  group  are  flattened,  creeping  plants,  or 
a  few  of  them  floating  aquatics,  without  distinct  stem  and 
leaves ;  but  the  higher  ones  have  a  pretty  well-developed  cen- 
tral axis  or  stem,  with  simple  leaves  attached. 

There  are  two  classes  —  I.  Liverworts  (Hepaticce) ,  and  II. 
Mosses  (Musci). 

CLASS  I. — THE  LIVERWORTS. 

One  of  the  commonest  of  this  class,  and  to  be  had  at  any 
time,  is  named  Madotheca.  It  is  one  of  the  highest  of  the 
class,  having  distinct  stem  and  leaves.  It  grows  most  com- 
monly on  the  shady  side  of  tree  trunks,  being  most  luxuriant 
near  the  ground,  where  the  supply  of  moisture  is  most  con- 
stant. It  also  occurs  on  stones  and  rocks  in  moist  places. 
It  closely  resembles  a  true  moss  in  general  appearance,  and 
from  the  scale-like  arrangement  of  its  leaves  is  sometimes 
called  "  scale  moss." 

86 


BRYOPHTTA.  87 

The  leaves  (Fig.  52,  A,  B)  are  rounded  in  outline  unequally, 
two-lobed,  and  arranged  in  two  rows  on  the  upper  side  of  the 
stem,  so  closely  overlapping  as  to  conceal  it  entirely.  On  the 
under  side  are  similar  but  smaller  leaves,  less  regularly  dis- 
posed. The  stems  branch  at  intervals,  the  branches  spreading 
out  laterally  so  that  the  whole  plant  is  decidedly  flattened. 
On  the  under  side  are  fine,  whitish  hairs,  that  fasten  it  to  the 
substratum.  If  we  examine  a  number  of  specimens,  especially 
early  in  the  spring,  a  difference  will  be  observed  in  the  plants. 
Some  of  them  will  be  found  to  bear  peculiar  structures  (Fig. 


*  3) 


FIG.  52.  —  A,  part  of  a  plant  of  a  leafy  liverwort  (Madotheca),  x  2.  B,  part  of 
the  same,  seen  from  below,  x  4.  C,  a  branch  with  two  open  sporogonia  (sp.), 
x  4.  D,  a  single  sporogonium,  x  8. 

52,  (7,  D),  in  which  the  spores  are  produced.  These  are  called 
"  sporogonia."  They  are  at  first  globular,  but  when  ripe  open 
by  means  of  four  valves,  and  discharge  a  greenish  brown  mass 
of  spores.  An  examination  of  the  younger  parts  of  the  same 
plants  will  probably  show  small  buds  (Fig.  54,  H),  which  con- 
tain the  female  reproductive  organs,  from  which  the  sporogonia 
arise. 

On  other  plants  may  be  found  numerous  short  side  branches 
(Fig.  53,  .B),  with  very  closely  set  leaves.  If  these  are  care- 
fully separated,  the  antheridia  can  just  be  seen  as  minute 
whitish  globules,  barely  visible  to  the  naked  eye.  Plants  that, 


88  BOTANY. 

like  this  one,  have  the  male  and  female  reproductive  organs  on 
distinct  plants,  are  said  to  be  "  dioecious.77 

A  microscopical  examination  of  the  stem  and  leaves  shows  their  struct- 
ure to  be  very  simple.  The  former  is  cylindrical,  and  composed  of  nearly 
uniform  elongated  cells,  with  straight  cross-walls.  The  leaves  consist  of  a 
single  layer  of  small,  roundish  cells,  which,  like  those  of  the  stem,  contain 
numerous  rounded  chloroplasts,  to  which  is  due  their  dark  green  color. 

The  tissues  are  developed  from  a  single  apical  cell,  but  it  is  difficult  to 
obtain  good  sections  through  it. 

The  antheridia  are  borne  singly  at  the  bases  of  the  leaves  on  the  special 
branches  already  described  (Fig.  53,  A,  an.).  By  carefully  dissecting  with 


an.- — 


FIG.  53.  —  A,  end  of  a  branch  from  a  male  plant  of  Madotheca.  The  small  side 
branchlets  bear  the  antheridia,  x  2.  B,  two  young  antheridia  (an.),  the 
upper  one  seen  in  optical  section,  the  lower  one  from  without,  x  150.  C,  a 
ripe  antheridium,  optical  section,  x  50.  D,  sperm  cells  with  young  sperma- 
tozoids.  E,  ripe  spermatozoids,  x  600. 

needles  such  a  branch  in  a  drop  of  water,  some  of  the  antheridia  will 
usually  be  detached  uninjured,  and  may  be  readily  studied,  the  full-grown 
ones  being  just  large  enough  to  be  seen  with  the  naked  eye.  They  are 
globular  bodies,  attached  by  a  stalk  composed  of  two  rows  of  cells.  The 
globular  portion  consists  of  a  wall  of  chlorophyll-bearing  cells,  composed 
of  two  layers  below,  but  single  above  (Fig.  53,  C).  Within  is  a  mass  of 
excessively  small  cells,  each  of  which  contains  a  spermatozoid.  In  the 
young  antheridium  (.4,  an.)  the  wall  is  single  throughout,  and  the  central 
cells  few  in  number.  To  study  them  in  their  natural  position,  thin  longi- 
tudinal sections  of  the  antheridial  branch  should  be  made. 

When  ripe,  if  brought  into  water,  the  antheridium  bursts  at  the  top  into 


BRYOPHYTA. 


89 


a  number  of  irregular  lobes  that  curl  back  and  allow  the  mass  of  sperm 
cells  to  escape.  The  spermatozoids,  which  are  derived  principally  from 
the  nucleus  of  the  sperm  cells  (53,  D)  are  so  small  as  to  make  a  satis- 
factory examination  possible  only  with  very  powerful  lenses.  The  ripe 
spermatozoid  is  coiled  in  a  flat  spiral  (53,  E),  and  has  two  excessively 
delicate  cilia,  visible  only  under  the  most  favorable  circumstances. 

The  female  organ  in  the  bryophytes  is  called  an  "archegonium,"  and 
differs  considerably  from  anything  we  have  yet  studied,  but  recalls 
somewhat  the  structure  of  the  oogonium  of  Cham.  They  are  found  in 


C 


FIG.  54.  —  A-D,  development  of  the  archegonium  of  Madotheca.  B,  surface 
view,  the  others  in  optical  section,  o,  egg  cell,  x  150.  E,  base  of  a  fertilized 
archegonium,  containing  a  young  embryo  (em.),  x  150.  F,  margin  of 
one  of  the  leaves  surrounding  the  archegonia.  G,  young  sporogonium  still 
surrounded  by  the  much  enlarged  base  of  the  archegonium.  h,  neck  of  the 
archegonium.  ar.  abortive  archegonia,  x  12.  H,  short  branch  containing 
the  young  sporogonium,  x  4. 


groups,  contained  in  little  bud- like  branches  (54,  H).  In  order  to  study 
them,  a  plant  should  be  chosen  that  has  numbers  of  such  buds,  and  the 
smallest  that  can  be  found  should  be  used.  Those  containing  the  young 
archegonia  are  very  small ;  but  after  one  has  been  fertilized,  the  leaves 
enclosing  it  grow  much  larger,  and  the  bud  becomes  quite  conspicuous, 
being  surrounded  by  two  or  three  comparatively  large  leaves.  By  dissect- 
ing the  young  buds,  archegonia  in  all  stages  of  growth  may  be  found. 

When  very  young  the  archegonium  is  composed  of  an  axial  row  of  three 
cells,  surrounded  by  a  single  outer  layer  of  cells,  the  upper  ones  forming 
five  or  six  regular  rows,  which  are  somewhat  twisted  (Fig.  54,  A,  B).  As 
it  becomes  older,  the  lower  part  enlarges  slightly,  the  whole  looking  some- 
thing like  a  long-necked  flask  (C,  D).  The  centre  of  the  neck  is  occupied 


90 


BOTANY. 


by  a  single  row  of  cells  (canal  cells),  with  more  granular  contents  than  the 
outer  cells,  the  lowest  cell  of  the  row  being  somewhat  larger  than  the 

others  (Fig.  54,  C,  o).  When  nearly 
ripe,  the  division  walls  of  the" canal 
cells  are  absorbed,  and  the  proto- 
plasm of  the  lowest  cell  contracts 
and  forms  a  globular  naked  cell, 
the  egg  cell  (Z),  o).  If  a  ripe  arche- 
gonium  is  placed  in  water,  it  soon 
opens  at  the  top,  and  the  contents  of 
the  canal  cells  are  forced  out,  leav- 
ing a  clear  channel  down  to  the  egg 
cell.  If  the  latter  is  not  fertilized, 
the  inner  walls  of  the  neck  cells 
turn  brown,  and  the  egg  cell  dies  ; 
but  if  a  spermatozoid  penetrates 
to  the  egg  cell,  the  latter  develops 
a  wall  and  begins  to  grow,  forming 
the  embryo  or  young  sporogonium. 
The  first  division  wall  to  be  formed 
in  the  embryo  is  transverse,  and  is 
folio  wed  by  vertical  ones  (Fig.  54,  E, 
em.).  As  the  embryo  enlarges,  the 

walls  of  the  basal  part  of  the  archegonium  grow  rapidly,  so  that  the  em- 
bryo remains  enclosed  in  the  archegonium  until  it  is  nearly  full-grown 

(Fig.  55).  As  it  increases  in  size,  it 
becomes  differentiated  into  three  parts : 
a  wedge-shaped  base  or  "  foot "  pene- 
trating downward  into  the  upper  part 
of  the  plant,  and  serving  to  supply 
the  embryo  with  nourishment ;  second, 
a  stalk  supporting  the  third  part,  the 
capsule  or  spore- bearing  portion  of  the 
fruit.  The  capsule  is  further  differen- 
tiated into  a  wall,  which  later  becomes 
dark  colored,  and  a  central  cavity,  in 
which  are  developed  special  cells,  some 
of  which  by  further  division  into  four 
parts  produce  the  spores,  while  the 
others,  elongating  enormously,  give  rise 
to  special  cells, called  elaters  (Fig.  56,.B). 


FIG.  55.  —  Longitudinal  section  of  a 
nearly  full-grown  sporogonium  of 
Madotheca,  which  has  not,  however, 
broken  through  the  overlying  cells, 
x  25.  sp.  cavity  in  which  the  spores 
are  formed,  ar.  abortive  arche- 
gonium. 


FIG.    56.  —  Spore   (.4)    and    two 
elaters  (jB)  of  Madotheca,  x  300. 


BEYOPHYTA.  91 

The  ripe  spores  are  nearly  globular,  contain  chlorophyll  and  drops  of 
oil,  and  the  outer  wall  is  brown  and  covered  with  fine  points  (Fig.  56,  A). 
The  elaters  are  long-pointed  cells,  having  on  the  inner  surface  of  the  wall 
a  single  or  double  dark  brown  spiral  band.  These  bands  are  susceptible 
to  changes  in  moisture,  and  by  their  movements  probably  assist  in  scatter- 
ing the  spores  after  the  sporogonium  opens. 

Just  before  the  spores  are  ripe,  the  stalk  of  the  sporogo- 
nium elongates  rapidly,  carrying  up  the  capsule,  which  breaks 
through  the  archegonium  wall,  and  finally  splits  into  four 
valves,  and  discharges  the  spores. 

There  are  four  orders  of  the  liverworts  represented  in  the 
United  States,  three  of  which  differ  from  the  one  we  have 
studied  in  being  flattened  plants,  without  distinct  stems  and 
leaves,  —  at  least,  the  leaves  when  present  are  reduced  to  little 
scales  upon  the  lower  surface. 

The  first  order  (Ricciacece)  are  small  aquatic  forms,  or  grow 
on  damp  ground  or  rotten  logs.  They  are  not  common  forms, 
and  not  likely  to  be  encountered  by  the  student.  One  of  the 
floating  species  is  shown  in  figure  57,  A. 

The  second  order,  the  horned  liverworts  (Anthocerotece) ,  are 
sometimes  to  be  met  with  in  late  summer  and  autumn,  forms 
growing  mostly  on  damp  ground,  and  at  once  recognizable 
by  their  long-pointed  sporogonia,  which  open  when  ripe  by  two 
valves,  like  a  bean  pod  (Fig.  57,  B). 

The  third  order  (Marcliantiacece)  includes  the  most  con- 
spicuous members  of  the  whole  class.  Some  of  them,  like  the 
common  liverwort  (Marchantia) ,  shown  in  Figure  57,  F,  K,  and 
the  giant  liverwort  (Fig.  57,  D),  are  large  and  common  forms, 
growing  on  the  ground  in  shady  places,  the  former  being  often 
found  also  in  greenhouses.  They  are  fastened  to  the  ground 
by  numerous  fine,  silky  hairs,  and  the  tissues  are  well  differenti- 
ated, the  upper  surface  of  the  plant  having  a  well-marked 
epidermis,  with  peculiar  breathing  pores,  large  enough  to  be 
seen  with  the  naked  eye  (Fig.  57,  E,  j,  K).  Each  of  these  is 
situated  in  the  centre  of  a  little  area  (Fig.  57,  E),  and  beneath 


92 


BOTANY. 


it  is  a  large  air  space,  into  which  the  chlorophyll-bearing  cells 
(cZ.)  of  the  plant  project  (J). 

The  sexual  organs  are  often  produced  in  these  forms  upon 
special  branches  (G),  or  the  antheridia  may  be  sunk  in  discs 
on  the  upper  side  of  the  stem  (Z),  an.). 


FIG.  57.  — Forms  of  liverworts.  A,  Riccia,  natural  size.  S,  Anthoceros 
(horned  liverwort),  natural  size.  sp.  sporogonia.  C,  Lumtlaria,  natural 
size,  x,  buds.  Z>,  giant .liverwort  (Conocephalus),  natural  size.  an.  anthe- 
ridial  disc.  E,  small  piece  of  the  epidermis,  showing  the  breathing  pores, 
x  2.  F,  common  liverwort  (Marchantia) ,  x  2.  x,  cups  containing  buds.  G, 
archegonial  branch  of  common  liverwort,  natural  size.  H,  two  young  buds 
from  the  common  liverwort,  x  150.  /,  a  full-grown  bud,  x  25.  J,  vertical 
section  through  the  body  of  Marchantia,  cutting  through  a  breathing  pore  (s), 
x  50.  K,  surface  view  of  a  breathing  pore,  x  150.  L,  a  leafy  liverwort 
(Jungermannia) .  sp.  sporogonium,  x  2. 

Some  forms,  like  Marchantia  and  Lunularia  (Fig.  57,  (7), 
produce  little  cups  (x) ,  circular  in  the  first,  semicircular  in  the 
second,  in  which  special  buds  (//,  /)  are  formed  that  fall  off 
and  produce  new  plants. 

The  highest  of  the  liverworts   (Jungermanniacece)  are,  for 


BKYOPHYTA.  93 

the  most  part,  leafy  forms  like  Madotheca,  and  represented 
by  a  great  many  common  forms,  growing  usually  on  tree 
trunks,  etc.  They  are  much  like  Madotheca  in  general  appear- 
ance, but  usually  very  small  and  inconspicuous,  so  as  to  be 
easily  overlooked,  especially  as  their  color  is  apt  to  be  brownish, 
and  not  unlike  that  of  the  bark  on  which  they  grow  (Fig. 
57,  L). 

CLASS  II.  —  THE  TRUE  MOSSES. 

The  true  mosses  (Musci)  resemble  in  many  respects  the 
higher  liverworts,  such  as  Madotheca  or  Jungermannia,  all  of 
them  having  well-marked  stems  and  leaves.  The  spore  fruit 
is  more  highly  developed  than  in  the  liverworts,  but  never  con- 
tains elaters. 

A  good  idea  of  the  general  structure  of  the  higher  mosses 
may  be  had  from  a  study  of  almost  any  common  species.  One 
of  the  most  convenient,  as  well  as  common,  forms  (Funarid)  is 
to  be  had  almost  the  year  round,  and  fruits  at  almost  all 
seasons,  except  midwinter.  It  grows  in  close  patches  on  the 
ground  in  fields,  at  the  bases  of  walls,  sometimes  in  the  crevices 
between  the  bricks  of  sidewalks,  etc.  If  fruiting,  it  may  be 
recognized  by  the  nodding  capsule  on  a  long  stalk,  that  is  often 
more  or  less  twisted,  being  sensitive  to  changes  in  the  moisture 
of  the  atmosphere.  The  plant  (Fig.  '58,  A,  E)  has  a  short 
stem,  thickly  set  with  relatively  large  leaves.  These  are 
oblong  and  pointed,  and  the  centre  is  traversed  by  a  delicate 
midrib.  The  base  of  the  stem  is  attached  to  the  ground  by 
numerous  fine  brown  hairs. 

The  mature  capsule  is  broadly  oval  in  form  (Fig.  58,  O),  and 
provided  with  a  lid  that  falls  off  when  the  spores  are  ripe. 
While  the  capsule  is  young  it  is  covered  by  a  pointed  mem- 
branous cap  (JB,  cal.)  that  finally  falls  off.  When  the  lid  is 
removed,  a  fine  fringe  is  seen  surrounding  the  opening  of  the 
capsule,  and  serving  the  same  purpose  as  the  elaters  of  the 
liverworts  (Fig.  58,  E). 


94 


BOTANY. 


If  the  lower  part  of  the  stem  is  carefully  examined  with  a 
lens,  we  may  detect  a  number  of  fine  green  filaments  growing 
from  it,  looking  like  the  root  hairs,  except  for  their  color. 
Sometimes  the  ground  about  young  patches  of  the  moss  is 
quite  covered  by  a  fine  film  of  such  threads,  and  looking  care- 


sp. 


FIG.  58.  —  A,  fruiting  plant  of  a  moss  (Funaria),  with  young  sporogonium 
(sp.),  x  4.  B,  plant  with  ripe  sporogonium.  col.  calyptra,  x  2.  C,  sporo- 
gonium with  calyptra  removed,  op.  lid,  x  4.  Z),  spores  :  i,  ungerminated ; 
n-iv,  germinating,  x  300.  Et  two  teeth  from  the  margin  of  the  capsule,  x  50. 
F,  epidermal  cells  and  breathing  pore  from  the  surface  of  the  sporogonium, 
x  150.  G,  longitudinal  section  of  a  young  sporogonium,  x  12.  sp.  spore 
mother  cells.  H,  a  small  portion  of  G,  magnified  about  300  times,  sp.  spore 
mother  cells. 

fully  over  it  probably  very  small  moss  plants  may  be  seen 
growing  up  here  and  there  from  it. 

This  moss  is  dioecious.  The  male  plants  are  smaller  than  the 
female,  and  may  be  recognized  by  the  bright  red  antheridia 
which  are  formed  at  the  end  of  the  stem  in  considerable  num- 
bers, and  surrounded  by  a  circle  of  leaves  so  that  the  whole 


BRYOPHYTA. 


95 


looks  something  like  a  flower.      (This  is  still  more  evident  in 
some  other  mosses.     See  Figure  65,  E,  F.) 

The  leaves  when  magnified  are 
seen  to  be  composed  of  a  single  layer 
of  cells,  except  the  midrib,  which  is 
made  up  of  several  thicknesses  of 
elongated  cells.  Where  the  leaf  is 
one  cell  thick,  the  cells  are  oblong  in 
form,  becoming  narrower  as  they  ap- 
proach the  midrib  and  the  margin. 
They  contain  numerous  chloroplasts 
imbedded  in  the  layer  of  protoplasm 
that  lines  the  wall.  The  nucleus  (Fig. 
63,  (7,  ri)  may  usually  be  seen  with- 
out difficulty,  especially  if  the  leaf 
is  treated  with  iodine.  This  plant  is 
one  of  the  best  for  studying  the  di- 
vision of  the  chloroplasts,  which  may 
usually  be  found  in  all  stages  of  divis- 
ion (Fig.  63,  D).  In  the  chloroplasts, 
especially  if  the  plant  has  been  ex- 
posed to  light  for  several  hours,  will 
be  found  numerous  small  granules, 

that  assume  a  bluish  tint  on  the  application  of  iodine,  showing  them 
to  be  starch  grains.  If  the  plant  is  kept  in  the  dark  for  a  day  or  two, 
these  will  be  absent,  having  been  used  up  ; 
but  if  exposed  to  the  light  again,  new 
ones  will  be  formed,  showing  that  they 
are  formed  only  under  the  action  of  light. 

Starch  is  composed  of  carbon,  hydro- 
gen, and  oxygen,  and  so  far  as  is  known 
is  only  produced  by  chlorophyll-bearing 
cells,  under  the  influence  of  light.  The 
carbon  used  in  the  manufacture  of  starch 
is  taken  from  the  atmosphere  in  the  form 
of  carbonic  acid,  so  that  green  plants  serve 
to  purify  the  atmosphere  by  the  removal 
of  this  substance,  which  is  deleterious  to 
animal  life,  while  at  the  same  time  the 
carbon,  an  essential  part  of  all  living 


FIG.  59.  —  Longitudinal  section 
through  the  summit  of  a  small 
male  plant  of  Funaria.  a,  a', 
antheridia.  p,  paraphysis.  L,  sec- 
tion of  a  leaf,  x  150. 


FIG.  60. — A,  S,  young  anthe- 
ridia of  Funaria,  optical 
section,  x  150.  C,  two  sperm 
cells  of  Atrichum.  D,  sper- 
matozoids  of  Sphagnum. 
x600. 


96  BOTANY. 

matter,  is  combined  in  such  form  as  to  make  it  available  for  the  food  of 
other  organisms. 

The  marginal  cells  of  the  leaf  are  narrow,  and  some  of  them  prolonged 
into  teeth. 

A  cross-section  of  the  stem  (63,  E)  shows  on  the  outside  a  single  row  of 
epidermal  cells,  then  larger  chlorophyll-bearing  cells,  and  in  the  centre  a 
group  of  very  delicate,  small,  colorless  cells,  which  in  longitudinal  section 
are  seen  to  be  elongated,  and  similar  to  those  forming  the  midrib  of  the 
leaf.  These  cells  probably  serve  for  conducting  fluids,  much  as  the 
similar  but  more  perfectly  developed  bundles  of  cells  (fibre-vascular 
bundles)  found  in  the  stems  and  leaves  of  the  higher  plants. 

The  root  hairs,  fastening  the  plant  to  the  ground,  are  rows  of  cells  with 
brown  walls  and  oblique  partitions.  They  often  merge  insensibly  into  the 
green  filaments  (protonema)  already  noticed.  These  latter  have  usually 
colorless  walls,  and  more  numerous  chloroplasts,  looking  very  much  like 
a  delicate  specimen  of  Cladophora  or  some  similar  alga.  If  a  sufficient 
number  of  these  filaments  is  examined,  some  of  them  will  probably  show 
young  moss  plants  growing  from  them  (Fig.  63,  A,  &),  and  with  a  little 
patience  the  leafy  plant  can  be  traced  back  to  a  little  bud  originating  as 
a  branch  of  the  filament.  Its  diameter  is  at  first  scarcely  greater  than 
that  of  the  filament,  but  a  series  of  walls,  close  together,  are  formed,  so 
placed  as  to  cut  off  a  pyramidal  cell  at  the  top,  forming  the  apical  cell  of 
the  young  moss  plant.  This  apical  cell  has  the  form  of  a  three-sided 
pyramid  with  the  base  upward.  From  it  are  developed  three  series  of 
cells,  cut  off  in  succession  from  the  three  sides,  and  from  these  cells  are 
derived  all  the  tissues  of  the  plant  which  soon  becomes  of  sufficient  size 
to  be  easily  recognizable. 

The  protonemal  filaments  may  be  made  to  grow  from  almost  any  part 
of  the  plant  by  keeping  it  moist,  but  grow  most  abundantly  from  the 
base  of  the  stem. 

The  sexual  organs  are  much  like  those  of  the  liverworts  and  are  borne 
at  the  apex  of  the  stems. 

The  antheridia  (Figs.  59,  60)  are  club-shaped  bodies  with  a  short  stalk. 
The  upper  part  consists  of  a  single  layer  of  large  chlorophyll-bearing  cells, 
enclosing  a  mass  of  very  small,  nearly  cubical,  colorless,  sperm  cells  each 
of  which  contains  an  excessively  small  spermatozoid. 

The  young  antheridium  has  an  apical  cell  giving  rise  to  two  series  of 
segments  (Fig.  60,  A),  which  in  the  earlier  stages  are  very  plainly  marked. 

When  ripe  the  chlorophyll  in  the  outer  cells  changes  color,  becoming 
red,  and  if  a  few  such  antheridia  from  a  plant  that  has  been  kept  rather 
dry  for  a  day  or  two,  are  teased  out  in  a  drop  of  water,  they  will  quickly 


BEYOPHYTA. 


97 


open  at  the  apex,  the  whole  mass  of  sperm  cells  being  discharged  at 
once. 

Among  the  antheridia  are  borne  peculiar  hairs  (Fig.  59,  p)  tipped  by 
a  large  globular  cell. 

D 


FIG.  61.—  A,  B,  young;    C,  nearly  ripe  archegonium  of  Funaria,  optical 
section,  x  150.    D,  upper  part  of  the  neck  of  C,  seen  from  without,  showing 


how  it  is  twisted.    E,  hase  of  a  ripe  archegonium. 
same,  x  150.    o,  egg  cell,    b,  ventral  canal  cell. 


F,  open  apex  of  the 


Owing  to  their  small  size  the  spermatozoids  are  difficult  to  see  satis- 
factorily and  other  mosses  (e.g.  peat  mosses,  Figure  64,  the  hairy  cap 
moss,  Figure  65,  /),  are  preferable  where  obtainable.  The  spermatozoids 
of  a  peat  moss  are  shown  in  Figure  60,  D.  Like  all  of  the  bryophytes 
they  have  but  two  cilia. 

The  archegonia  (Fig.  61)  should 
be  looked  for  in  the  younger  plants  in 
the  neighborhood  of  those  that  bear 
capsules.  Like  the  antheridia  they 
occur  in  groups.  They  closely  resem- 
ble those  of  the  liverworts,  but  the 
neck  is  longer  and  twisted  and  the 
base  more  massive.  Usually  but 
a  single  one  of  the  group  is  fertilized. 

To  study  the  first  division  of  the 
embryo,  it  is  usually  necessary  to 
render  the  archegonium  transparent, 
which  may  be  done  by  using  a  little 

caustic  potash ;  or  letting  it  lie  for  a  few  hours  in  dilute  glycerine  will 
sometimes  suffice.  If  potash  is  used  it  must  be  thoroughly  washed  away, 
by  drawing  pure  water  under  the  cover  glass  with  a  bit  of  blotting  paper, 


FIG.  62.  —  A,  young  embryo  of 
Funaria,  still  enclosed  within  the 
base  of  the  archegonium,  x  300. 
B,  an  older  embryo  freed  from  the 
archegonium,  x  150.  a,  the  apical 
cell. 


98 


BOTANY. 


until  every  trace  of  the  potash  is  removed.  The  first  wall  in  the  embryo 
is  nearly  at  right  angles  to  the  axis  of  the  archegonium  and  divides  the 
egg  cell  into  nearly  equal  parts.  This  is  followed  by  nearly  vertical  walls 
in  each  cell  (Fig.  62,  A).  Very  soon  a  two-sided  apical  cell  (Fig.  62, 
B,  a)  is  formed  in  the  upper  half  of  the  embryo,  which  persists  until  the 
embryo  has  reached  a  considerable  size.  As  in  the  liverworts  the  young 
embryo  is  completely  covered  by  the  growing  archegonium  wall. 

The  embryo  may  be  readily  removed  from  the  archegonium  by  adding 
a  little  potash  to  the  water  in  which  it  is  lying,  allowing  it  to  remain  for 
a  few  moments  and  pressing  gently  upon  the  cover  glass  with  a  needle. 
In  this  way  it  can  be  easily  forced  out  of  the  archegonium,  and  then  by 
thoroughly  washing  away  the  potash,  neutralizing  if  necessary  with  a  little 
acetic  acid,  very  beautiful  preparations  may  be  made.  If  desired,  these 
may  be  mounted  permanently  in  glycerine  which,  however,  must  be  added 
very  gradually  to  avoid  shrinking  the  cells. 

For  some  time  the  embryo  has  a  nearly  cylindrical  form,  but  as  it 

approaches  maturity 
the  differentiation 
into  stalk  and  cap- 
sule becomes  appar- 
ent. The  latter  in- 
creases rapidly  in 
diameter,  assuming 
gradually  the  oval 
shape  of  the  full- 
grown  capsule.  A 
longitudinal  section 
of  the  nearly  ripe 
capsule  (Fig.  58,  (r) 
shows  two  distinct 
portions;  an  outer 
wall  of  two  layers  of 
cells,  and  an  inner 
mass  of  cells  in  some 


FIG.  63.  —  A,  protonema  of  Funaria,  with  a  bud 
x  50.  B,  outline  of  a  leaf,  showing  also  the  thickened 
midrib,  x  12.  (7,  cells  of  the  leaf,  x  300.  n,  nucleus. 

D,  chlorophyll  granules  undergoing  division,  x  300. 

E,  cross-section  of  the  stem,  x  50. 


of  which  the  spores  are  produced.  This  inner  mass  of  cells  is  continuous 
with  the  upper  part  of  the  capsule,  but  connected  with  the  side  walls  and 
bottom  by  means  of  slender,  branching  filaments  of  chlorophyll-bearing 
cells. 

The  spores  arise  from  a  single  layer  of  cells  near  the  outside  of  the 
inner  mass  of  cells  (G,  sp.).  These  cells  (H,  sp.)  are  filled  with  glis- 
tening, granular  protoplasm ;  have  a  large  and  distinct  nucleus,  and  no 


BRYOPHTTA. 


99 


chlorophyll.  They  finally  become  entirely  separated  and  each  one  gives 
rise  to  four  spores  which  closely  resemble  those  of  the  liverworts  but  are 
smaller. 

Near  the  base  of  the  capsule,  on  the  outside,  are  formed  breathing 
pores  (Fig.  58,  F)  quite  similar  to  those  of  the  higher  plants. 

If  the  spores  are  kept  in  water  for  a  few  days  they  will  germinate, 
bursting  the  outer  brown  coat,  and  the  contents  protruding  through  the 
opening  surrounded  by  the  colorless  inner  spore  membrane.  The  pro- 
tuberance grows  rapidly  in  length  and  soon  becomes  separated  from  the 
body  of  the  spore  by  a  wall,  and  lengthening,  more  and  more,  gives  rise 
to  a  green  filament  like  those  we  found  attached  to  the  base  of  the  full- 
grown  plant,  and  like  those  giving  rise  to  buds  that  develop  into  leafy 
plants. 

CLASSIFICATION  OF  THE  MOSSES. 

The  mosses  may  be  divided  into  four  orders  :  I.  The  peat 
mosses  (Sphagnacece)-,  II.  Andreceacece  ;  III.  Phascacece;  IV. 
The  common  mosses  (Bryacece). 


C 


FIG.  64.  —  A,  a  peat  moss  (Sphagnum),  x  l/2.  B,  a  sporogonium  of  the  same, 
x  3.  C,  a  portion  of  a  leaf,  x  150.  The  narrow,  chlorophyll-bearing  cells 
form  meshes,  enclosing  the  large,  colorless  empty  cells,  whose  walls  are 
marked  with  thickened  bars,  and  contain  round  openings  (o). 

The  peat  mosses  (Fig.  64)  are  large  pale-green  mosses,  grow- 
ing often  in  enormous  masses,  forming  the  foundation  of  peat- 
bogs. They  are  of  a  peculiar  spongy  texture,  very  light  when 
dry,  and  capable  of  absorbing  a  great  amount  of  water.  They 
branch  freely  (Fig.  64,  A),  the  branches  being  closely  crowded 


100 


BOTANY. 


at  the  top,  where  the  stems  continue  to  grow,  dying  away 
below. 

The  sexual  organs  are  rarely  met  with,  but  should  be  looked 
for  late  in  autumn  or  early  spring.  The  antheridial  branches 
are  often  bright-colored,  red  or  yellow,  so  as  to  be  very  con- 
spicuous. The  capsules,  which  are  not  often  found,  are  larger 


n 


FIG.  65.  —  Forms  of  mosses.  A,  plant  of  Phascvm,  x  3.  B,  fruiting  plant  of 
Atrichum,  x  2.  (7,  young  capsule  of  hairy-cap  moss  (Polytrichum) ,  covered 
by  the  large,  hairy  calyptra.  D,  capsules  of  Bartramia  :  i,  with ;  n,  without 
the  calyptra.  E,  upper  part  of  a  male  plant  of  Atrichum,  snowing  the  flower, 
x  2.  F,  a  male  plant  of  Mnium,  x  4.  G,  pine-tree  moss  (Clemacium] I,  x  1. 
H.  Hypnum,  x  1.  /,  ripe  capsules  of  hairy-cap  moss :  i,  with  ;  u,  without 
calyptra. 

than  in  most  of  the  common  mosses,  and  quite  destitute  of  a 
stalk,  the  apparent  stalk  being  a  prolongation  of  the  axis  of 
the  plant  in  the  top  of  which  the  base  of  the  sporogonium 
is  imbedded.  The  capsule  is  nearly  globular,  opening  by  a 
lid  at  the  top  (Fig.  64,  E). 


BRYOPHYTA.  101 

A  microscopical  examination  of  the  leaves,  which  are  quite  destitute  of 
a  midrib,  shows  them  to  be  composed  of  a  network  of  narrow  chlorophyll- 
bearing  cells  surrounding  much  larger  empty  ones  whose  walls  are  marked 
with  transverse  thickenings,  and  perforated  here  and  there  with  large, 
round  holes  (Fig.  64,  (7).  It  is  to  the  presence  of  these  empty  cells  that 
the  plant  owes  its  peculiar  spongy  texture,  the  growing  plants  being  fairly 
saturated  with  water. 

The  Andreceacece  are  very  small,  and  not  at  all  common.  The 
capsule  splits  into  four  valves,  something  like  a  liverwort. 

The  Phascacece  are  small  mosses  growing  on  the  ground  or 
low  down  on  the  trunks  of  trees,  etc.  They  differ  principally 
from  the  common  mosses  in  having  the  capsule  open  irregu- 
larly and  not  by  a  lid.  The  commonest  forms  belong  to  the 
genus  Phascum  (Fig.  65,  A). 

The  vast  majority  of  the  mosses  the  student  is  likely  to 
meet  with  belong  to  the  last  order,  and  agree  in  the  main  with 
the  one  described.  Some  of  the  commoner  forms  are  shown 
in  Figure  65. 


CHAPTER   XII. 


SUB-KINGDOM  V. 
PTERIDOPHYTES. 

IF  we  compare  the  structure  of  the  sporogonium  of  a  moss 
or  liverwort  with  the  plant  bearing  the  sexual  organs,  we  find 
that  its  tissues  are  better  differentiated,  and  that  it  is  on  the 
whole  a  more  complex  structure  than  the  plant  that  bears  it. 
It,  however,  remains  attached  to  the  parent  plant,  deriving  its 
nourishment  in  part  through  the  "foot"  by  means  of  which 
it  is  attached  to  the  plant. 

In  the  Pteridophytes,  however,  we  find  that  the  sporogo- 
nium becomes  very  much  more  developed,  and  finally  becomes 
entirely  detached  from  the  sexual  plant,  developing  in  most 
cases  roots  that  fasten  it  to  the  ground,  after  which  it  may  live 
for  many  years,  and  reach  a  very  large  size. 

The  sexual  plant,  which  is  here  called  the  "  prothallium,"  is  of 
very  simple  structure,  resembling  the  lower  liverworts  usually, 
and  never  reaches  more  than  about  a  centimetre  in  diameter, 
and  is  often  much  smaller  than  this. 

The  common  ferns  are  the  types  of  the  sub-kingdom,  and 
a  careful  study  of  any  of  these  will  illustrate  the  principal 
peculiarities  of  the  group.  The  whole  plant,  as  we  know  it, 
is  really  nothing  but  the  sporogonium,  originating  from  the 
egg  cell  in  exactly  the  same  way  as  the  moss  sporogonium,  and 
like  it  gives  rise  to  spores  which  are  formed  upon  the  leaves. 

The  spores  may  be  collected  by  placing  the  spore -bearing 
leaves  on  sheets  of  paper  and  letting  them  dry,  when  the  ripe 


PTERIDOPHYTES. 


103 


spores  will  be  discharged  covering  the  paper  as  a  fine,  brown 
powder.  If  these  are  sown  on  fine,  rather  closely  packed 
earth,  and  kept  moist  and  covered  with  glass  so  as  to  prevent 
evaporation,  within  a  week  or  two  a  fine,  green,  moss-like 
growth  will  make  its  appearance,  and  by  the  end  of  five  or  six 


FIG.  66.  —  A,  spore  of  the  ostrich  fern  (Onocled),  with  the  outer  coat  removed. 
B,  germinating  spore,  x  150.  (7,  young  prothallium,  x  50.  r,  root  hair.  sp. 
spore  membrane.  D,  E,  older  prothallia.  a,  apical  cell,  x  150.  F,  a  female 
prothallium,  seen  from  below,  x  12.  ar.  archegonia.  G,  H,  young  arche- 
gonia,  in  optical  section,  x  150.  o,  central  cell.  6,  ventral  canal  cell,  c, 
upper  canal  cell.  /,  a  ripe  archegonium  in  the  act  of  opening,  x  150.  o,  egg 
cell.  J,  a  male  prothallium,  x  50.  on.  antheridia.  K,  L,  young  antheridia, 
in  optical  section,  x  300.  M,  ripe  antheridium,  x  300.  sp.  sperm  cells.  2V,  0, 
antheridia  that  have  partially  discharged  their  contents,  x  300.  P,  sperma- 
tozoids,  killed  with  iodine,  x  500.  v,  vesicle  attached  to  the  hinder  end. 

weeks,  if  the  weather  is  warm,  little,  flat,  heart-shaped  plants 
of  a  dark-green  color  may  be  seen.  These  look  like  small 
liverworts,  and  are  the  sexual  plants  (prothallia)  of  our  ferns 
(Fig.  66,  F).  Kemoving  one  of  these  carefully,  we  find  on 
the  lower  side  numerous  fine  hairs  like  those  on  the  lower 


104  BOTANY. 

surface  of  the  liverworts,  which  fasten  it  firmly  to  the  ground. 
By  and  by,  if  our  culture  has  been  successful,  we  may  find 
attached  to  some  of  the  larger  of  these,  little  fern  plants  grow- 
ing from  the  under  side  of  the  prothallia,  and  attached  to  the 
ground  by  a  delicate  root.  As  the  little  plant  becomes  larger 
the  prothallium  dies,  leaving  it  attached  to  the  ground  as  an 
independent  plant,  which  after  a  time  bears  the  spores. 

In  choosing  spores  for  germination  it  is  best  to  select  those 
of  large  size  and  containing  abundant  chlorophyll,  as  they  ger- 
minate more  readily.  Especially  favorable  for  this  purpose 
are  the  spores  of  the  ostrich  fern  ( Onoclea  struthiopteris)  (Fig. 
70,  J,  J)j  or  the  sensitive  fern  (0.  sensibilis).  Another  com- 
mon and  readily  grown  species  is  the  lady  fern  (Asplenium  filix- 
foemina)  (Fig.  70,  H).  The  spores  of  most  ferns  retain  their 
vitality  for  many  months,  and  hence  can  be  kept  dry  until 
wanted. 

The  first  stages  of  germination  may  be  readily  seen  by  sowing  the 
spores  in  water,  where,  under  favorable  circumstances,  they  will  begin  to 
grow  within  three  or  four  days.  The  outer,  dry,  brown  coat  of  the  spore 
is  first  ruptured,  and  often  completely  thrown  off  by  the  swelling  of  the 
spore  contents.  Below  this  is  a  second  colorless  membrane  which  is  also 
ruptured,  but  remains  attached  to  the  spore.  Through  the  orifice  in  the 
second  coat,  the  inner  delicate  membrane  protrudes  in  the  form  of  a 
nearly  colorless  papilla  which  rapidly  elongates  and  becomes  separated 
from  the  body  of  the  spore  by  a  partition,  constituting  the  first  root  hair 
(Fig.  66,  B,  (7,  r).  The  body  of  the  spore  containing  most  of  the  chloro- 
phyll elongates  more  slowly,  and  divides  by  a  series  of  transverse  walls 
so  as  to  form  a  short  row  of  cells,  resembling  in  structure  some  of  the 
simpler  algae  (C). 

In  order  to  follow  the  development  furtner,  spores  must  be  sown  upon 
earth,  as  they  do  not  develop  normally  in  water  beyond  this  stage. 

In  studying  plants  grown  on  earth,  they  should  be  carefully  removed 
and  washed  in  a  drop  of  water  so  as  to  remove,  as  far  as  possible,  any 
adherent  particles,  and  then  may  be  mounted  in  water  for  microscopic 
examination. 

In  most  cases,  after  three  or  four  cross-walls  are  formed,  two  walls 
arise  in  the  end  cell  so  inclined  as  to  enclose  a  wedge-shaped  cell  (a)  from 
which  are  cut  off  two  series  of  segments  by  walls  directed  alternately 


PTEBIDOPHYTE8.  105 

right  and  left  (Fig.  66,  Z>,  E,  a),  the  apical  cell  growing  to  its  original 
dimensions  after  each  pair  of  segments  is  cut  off.  The  segments  divide 
by  vertical  walls  in  various  directions  so  that  the  young  plant  rapidly 
assumes  the  form  of  a  flat  plate  of  cells  attached  to  the  ground  by  root 
hairs  developed  from  the  lower  surfaces  of  the  cells,  and  sometimes  from 
the  marginal  ones.  As  the  division  walls  are  all  vertical,  the  plant  is 
nowhere  more  than  one  cell  thick.  The  marginal  cells  of  the  young  seg- 
ments divide  more  rapidly  than  the  inner  ones,  and  soon  project  beyond 
the  apical  cell  which  thus  comes  to  lie  at  the  bottom  of  a  cleft  in  the  front 
of  the  plant  which  in  consequence  becomes  heart-shaped  (E,,F).  Sooner 
or  later  the  apical  cell  ceases  to  form  regular  segments  and  becomes  indis- 
tinguishable from  the  other  cells. 

In  the  ostrich  fern  and  lady  fern  the  plants  are  dioecious.  The  male 
plants  (Fig.  66,  «7)  are  very  small,  often  barely  visible  to  the  naked  eye, 
and  when  growing  thickly  form  dense,  moss-like  patches.  They  are 
variable  in  form,  some  irregularly  shaped,  others  simple  rows  of  cells, 
and  some  have  the  heart  shape  of  the  larger  plants. 

The  female  plants  (Fig.  66,  F)  are  always  comparatively 
large  and  regularly  heart-shaped,  occasionally  reaching  a  diam- 
eter of  nearly  or  quite  one  centimetre,  so  that  they  are  easily 
recognizable  without  microscopical  examination. 

All  the  cells  of  the  plant  except  the  root  hairs  contain  large  and  distinct 
chloroplasts  much  like  those  in  the  leaves  of  the  moss,  and  like  them 
usually  to  be  found  in  process  of  division. 

The  archegonia  arise  from  cells  of  the  lower  surface,  just  behind  the 
notch  in  front  (Fig.  66,  F,  ar.).  Previous  to  their  formation  the  cells  at 
this  point  divide  by  walls  parallel  to  the  surface  of  the  plant,  so  as  to  form 
several  layers  of  cells,  and  from  the  lowest  layer  of  cells  the  archegonia 
arise.  They  resemble  those  of  the  liverworts  but  are  shorter,  and  the 
lower  part  is  completely  sunk  within  the  tissues  of  the  plant  (Fig.  66, 
6r,  /).  They  arise  as  single  surface  cells,  this  first  dividing  into  three  by 
walls  parallel  to  the  outer  surface.  The  lower  cell  undergoes  one  or  two 
divisions,  but  undergoes  no  further  change;  the  second  cell  (<7,  o), 
becomes  the  egg  cell,  and  from  it  is  cut  off  another  cell  (c),  the  canal  cell 
of  the  neck ;  the  uppermost  of  the  three  becomes  the  neck.  There  are 
four  rows  of  neck  cells,  the  two  forward  ones  being  longer  than  the  others, 
so  that  the  neck  is  bent  backward.  In  the  full-grown  archegonium,  there 
are  two  canal  cells,  the  lower  one  (//,  6)  called  the  ventral  canal  cell, 
being  smaller  than  the  other. 


106  BOTANY. 

Shortly  before  the  archegonium  opens,  the  canal  cells  become  disorgan- 
ized in  the  same  way  as  in  the  bryophytes,  and  the  protoplasm  of  the 
central  cell  contracts  to  form  the  egg  cell  which  shows  a  large,  central 
nucleus,  and  hi  favorable  cases,  a  clear  space  at  the  top  called  the  "recep- 
tive spot,"  as  it  is  here  that  the  spermatozoid  enters.  When  ripe,  if  placed 
in  water,  the  neck  cells  become  very  much  distended  and  finally  open 
widely  at  the  top,  the  upper  ones  not  infrequently  being  detached,  and 
the  remains  of  the  neck  cells  are  forced  out  (Fig.  66,  /). 

The  antheridia  (Fig.  66,  J,  M)  arise  as  simple  hemispherical  cells,  in 
which  two  walls  are  formed  (K  i,  n),  the  lower  funnel-shaped,  the  upper 
hemispherical  and  meeting  the  lower  one  so  as  to  enclose  a  central  cell 
(shaded  in  the  figure),  from  which  the  sperm  cells  arise.  Finally,  a  ring- 
shaped  wall  (L  in)  is  formed,  cutting  off  a  sort  of  cap  cell,  so  that  the 
antheridium  at  this  stage  consists  of  a  central  cell,  surrounded  by  three 
other  cells,  the  two  lower  ring-shaped,  the  upper  disc-shaped.  The  central 
cell,  which  contains  dense,  glistening  protoplasm,  is  destitute  of  chloro- 
phyll, but  the  outer  cells  have  a  few  small  chloroplasts.  The  former 
divides  repeatedly,  until  a  mass  of  about  thirty-two  sperm  cells  is  formed, 
each  giving  rise  to  a  large  spirally- coiled  spermatozoid.  When  ripe,  the 
mass  of  sperm  cells  crowds  so  upon  the  outer  cells  as  to  render  them 
almost  invisible,  and  as  they  ripen  they  separate  by  a  partial  dissolving 
of  the  division  walls.  When  brought  into  water,  the  outer  cells  of  the 
antheridium  swell  strongly,  and  the  matter  derived  from  the  dissolved 
walls  of  the  sperm  cells  also  absorbs  water,  so  that  finally  the  pressure 
becomes  so  great  that  the  wall  of  the  antheridium  breaks,  and  the  sperm 
cells  are  forced  out  by  the  swelling  up  of  the  wall  cells  (N,  0).  After 
lying  a  few  moments  in  the  water,  the  wall  of  each  sperm  cell  becomes 
completely  dissolved,  and  the  spermatozoids  are  released,  and  swim 
rapidly  away  with  a  twisting  movement.  They  may  be  killed  with  a  little 
iodine,  when  each  is  seen  to  be  a  somewhat  flattened  band,  coiled  several 
times.  At  the  forward  end,  the  coils  are  smaller,  and  there  are  numerous 
very  long  and  delicate  cilia.  At  the  hinder  end  may  generally  be  seen  a 
delicate  sac  (P,  -y),  containing  a  few  small  granules,  some  of  which  usually 
show  the  reaction  of  starch,  turning  blue  when  iodine  is  applied. 

In  studying  the  development  of  the  antheridia,  it  is  only  necessary  to 
mount  the  plants  in  water  and  examine  them  directly  ;  but  the  study  of 
the  archegonia  requires  careful  longitudinal  sections  of  the  prothallium. 
To  make  these,  the  prothallium  should  be  placed  between  small  pieces  of 
pith,  and  the  razor  must  be  very  sharp.  It  may  be  necessary  to  use  a  little 
potash  to  make  the  sections  transparent  enough  to  see  the  structure,  but 


PTERIDOPHYTES.  107 

this  must  be  used  cautiously  on  account  of  the  great  delicacy  of  the 
tissues. 

If  a  plant  with  ripe  archegonia  is  placed  in  a  drop  of  water,  with  the 
lower  surface  uppermost,  and  at  the  same  time  male  plants  arc  put  with 
it,  and  the  whole  covered  with  a  cover  glass,  the  archegonia  and  antheridia 
will  open  simultaneously  ;  and,  if  examined  with  the  microscope,  we  shall 
see  the  spermatozoids  collect  about  the  open  archegonia,  to  which  they 
are  attracted  by  the  substance  forced  out  when  it  opens.  With  a  little 
patience,  one  or  more  may  be  seen  to  enter  the  open  neck  through  which 
it  forces  itself,  by  a  slow  twisting  movement,  down  to  the  egg  cell.  In 
order  to  make  the  experiment  successful,  the  plants  should  be  allowed  to 
become  a  little  dry,  care  being  taken  that  no  water  is  poured  over  them 
for  a  day  or  two  beforehand. 

The  first  divisions  of  the  fertilized  egg  cell  resemble  those  in  the  moss 
embryo,  except  that  the  first  wall  is  parallel  with  the  archegonium  axis, 
instead  of  at  right  angles  to  it.  Very  soon,  however,  the  embryo  becomes 
very  different,  four  growing  points  being  established  instead  of  the  single 
one  found  in  the  moss  embryo.  The  two  growing  points  on  the  side  of 
the  embryo  nearest  the  archegonium  neck  grow  faster  than  the  others,  one 
of  these  outstripping  the  other,  and  soon  becoming  recognizable  as  the  first 
leaf  of  the  embryo  (Fig  67,  A,  L).  The  other  (r)  is  peculiar,  in  having  its 
growing  point  covered  by  several  layers  of  cells,  cut  off  from  its  outer  face, 
a  peculiarity  which  we  shall  find  is  characteristic  of  the  roots  of  all  the 
higher  plants,  and,  indeed,  this  is  the  first  root  of  the  young  fern.  Of  the 
other  two  growing  points,  the  one  next  the  leaf  grows  slowly,  forming  a  blunt 
cone  (st.),  and  is  the  apex  of  the  stem.  The  other  (/)  has  no  definite 
form,  and  serves  merely  as  an  organ  of  absorpti&n,  by  means  of  which 
nourishment  is  supplied  to  the  embryo  from  the  prothallium  ;  it  is  known 
as  the  foot. 

Up  to  this  point,  all  the  cells  of  the  embryo  are  much  alike,  and  the 
embryo,  like  that  of  the  bryophytes,  is  completely  surrounded  by  the 
enlarged  base  of  the  archegonium  (compare  Fig.  67,  A,  with  Fig.  55)  ;  but 
before  the  embryo  breaks  through  the  overlying  cells  a  differentiation  of 
the  tissues  begins.  In  the  axis  of  each  of  the  four  divisions  the  cells 
divide  lengthwise  so  as  to  form  a  cylindrical  mass  of  narrow  cells,  not 
unlike  those  in  the  stem  of  a  moss.  Here,  however,  some  of  the  cells 
undergo  a  further  change  ;  the  walls  thicken  in  places,  and  the  cells  lose 
their  contents,  forming  a  peculiar  conducting  tissue  (tracheary  tissue), 
found  only  in  the  two  highest  sub-kingdoms.  The  whole  central  cylinder 
is  called  a  "  fibro- vascular  bundle,"  an,d  in  its  perfect  form,  at  least,  is  found 
in  no  plants  below  the  ferns,  which  are  also  the  first  to  develop  true  roots. 


108 


BOTANY. 


The  young  root  and  leaf  now  rapidly  elongate,  and  burst 
through  the  overlying  cells,  the  former  growing  downward  and 
becoming  fastened  in  the  ground,  the  latter  growing  upward 
through  the  notch  in  the  front  of  the  prothallium,  and  increas- 


FIG. 67.  —  A,  embryo  of  the  ostrich  fern  just  before  breaking  through  the  pro- 
thallium,  x  50.  st.  apex  of  stem.  I,  first  leaf,  r,  first  root.  ar.  neck  of  the 
archegonium.  B,  young  plant,  still  attached  to  the  prothallium  (pr.).  C, 
underground  stem  of  the  maiden-hair  fern  (Adiantum),  with  one  young  leaf, 
and  the  base  of  an  older  one,  x  l.  D,  three  cross-sections  of  a  leaf  stalk  :  i, 
nearest  the  base ;  in,  nearest  the  blade  of  the  leaf,  showing  the  division  of 
the  fibro- vascular  bundle,  x  5.  E,  part  of  the  blade  of  the  leaf,  x  y2.  F,  a 
single  spore-bearing  leaflet,  showing  the  edge  folded  over  to  cover  the  spo- 
rangia, x  1.  Gf,  part  of  the  fibro-vascular  bundle  of  the  leaf  stalk  (cross- 
section),  x  50.  x,  woody  part  of  the  bundle,  y,  bast.  sfi.  bundle  sheath. 
H,  a  small  portion  of  the  same  bundle,  x  150.  I,  stony  tissue  from  the  under- 
ground stem,  x  150.  J,  sieve  tube  from  the  underground  stem,  x  300. 

ing  rapidly  in  size  (Fig.  67,  B).  The  leaf  is  more  or  less 
deeply  cleft,  and  traversed  by  veins  which  are  continuations  of 
the  fibro-vascular  bundle  of  the  stalk,  and  themselves  fork  once 
or  twice.  The  surface  of  the  leaf  is  covered  with  a  well- 
developed  epidermis,  and  the  cells  occupying  the  space  between 


PTERIDOPHYTES.  109 

the  veins  contain  numerous  chloroplasts,  so  that  the  little 
plant  is  now  quite  independent  of  the  prothallium,  which  has 
hitherto  supported  it.  As  soon  as  the  fern  is  firmly  established, 
the  prothallium  withers  away. 

Comparing  this  now  with  the  development  of  the  sporo- 
gonium  in  the  bryophytes,  it  is  evident  that  the  young  fern  is 
the  equivalent  of  the  sporogonium  or  spore  fruit  of  the  former, 
being,  like  it,  the  direct  product  of  the  fertilized  egg  cell ;  and 
the  prothallium  represents  the  moss  or  liverwort,  upon  which 
are  borne  the  sexual  organs.  In  the  fern,  however,  the  sporo- 
gonium becomes  entirely  independent  of  the  sexual  plant,  and 
does  not  produce  spores  until  it  has  reached  a  large  size,  living 
many  years.  The  sexual  stage,  on  the  other  hand,  is  very  much 
reduced,  as  we  have  seen,  being  so  small  as  to  be  ordinarily 
completely  overlooked ;  but  its  resemblance  to  the  lower  liver- 
worts, like  Riccia,  or  the  horned  liverworts,  is  obvious.  The 
terms  oophyte  (egg-bearing  plant)  and  sporophyte  (spore-bear- 
ing plant,  or  sporogonium)  are  sometimes  used  to  distinguish 
between  the  sexual  plant  and  the  spore-bearing  one  produced 
from  it. 

The  common  maiden-hair  fern  (Adiantum  pedatum)  has  been 
selected  here  for  studying  the  structure  of  the  full-grown 
sporophyte,  but  almost  any  other  common  fern  will  answer. 
The  maiden-hair  fern  is  common  in  rich*  woods,  and  may  be  at 
once  recognized  by  the  form  of  its  leaves.  These  arise  from  a 
creeping,  underground  stem  (Fig.  67,  C),  which  is  covered 
with  brownish  scales,  and  each  leaf  consists  of  a  slender  stalk, 
reddish  brown  or  nearly  black  in  color,  which  divides  into  two 
equal  branches  at  the  top.  Each  of  these  main  branches  bears 
a  row  of  smaller  ones  on  the  outside,  and  these  have  a  row  of 
delicate  leaflets  on  each  side  (Fig.  67,  E).  The  stem  of  the 
plant  is  fastened  to  the  ground  by  means  of  numerous  stout 
roots.  The  youngest  of  these,  near  the  growing  point  of  the 
stem,  are  unbranched,  but  the  older  ones  branch  extensively  (0). 

On  breaking  the  stem  across,  it  is  seen  to  be  dark-colored, 


110  BOTANY. 

except  in  the  centre,  which  is  traversed  by  a  woody  cylinder 
(fibro-vascular  bundle)  of  a  lighter  color.  This  is  sometimes 
circular  in  sections,  sometimes  horse-shoe  shaped.  Where  the 
stem  branches,  the  bundle  of  the  branch  may  be  traced  back 
to  where  it  joins  that  of  the  main  stem. 

A  thin  cross-section  of  the  stem  shows,  when  magnified,  three  regions. 
First,  an  outer  row  of  cells,  often  absent  in  the  older  portions ;  this  is  the 
epidermis.  Second,  within  the  epidermis  are  several  rows  of  cells  similar 
to  the  epidermal  cells,  but  somewhat  larger,  and  like  them  having  dark- 
brown  walls.  These  merge  gradually  into  larger  cells,  with  thicker  golden 
brown  walls  (Fig.  67,  /).  The  latter,  if  sufficiently  magnified,  show 
distinct  striation  of  the  walls,  which  are  often  penetrated  by  deep  narrow 
depressions  or  " pits."  This  thick- walled  tissue  is  called  "  stony  tissue" 
(schlerenchyma).  All  the  cells  contain  numerous  granules,  which  the 
iodine  test  shows  to  be  starch.  All  of  this  second  region  lying  between  the 
epidermis  and  the  fibro-vascular  bundle  is  known  as  the  ground  tissue. 
The  third  region  (fibro-vascular)  is,  as  we  have  seen  without  the  micro- 
scope, circular  or  horse-shoe  shaped.  It  is  sharply  separated  from  the 
ground  tissue  by  a  row  of  small  cells,  called  the  "bundle  sheath."  The 
cross-section  of  the  bundle  of  the  leaf  stalk  resembles,  almost  exactly,  that 
of  the  stem  ;  and,  as  it  is  much  easier  to  cut,  it  is  to  be  preferred  in  study- 
ing the  arrangement  of  the  tissues  of  the  bundle  (Fig.  67,  G).  Within  the 
bundle  sheath  (sh.)  there  are  two  well-marked  regions,  a  central  band  (x) 
of  large  empty  cells,  with  somewhat  angular  outlines,  and  distinctly 
separated  walls  ;  and  an  outer  portion  (y)  filling  up  the  space  between 
these  central  cells  and  the  bundle  sheath.  The  central  tissue  (x)  is  called 
the  woody  tissue  (xylem) ;  the  outer,  the  bast  (phloem).  The  latter  is 
composed  of  smaller  cells  of  variable  form,  and  with  softer  walls  than  the 
wood  cells. 

A  longitudinal  section  of  either  the  stem  or  leaf  stalk  shows  that  all  the 
cells  are  decidedly  elongated,  especially  those  of  the  fibro-vascular  bundle. 
The  xylem  (Fig.  68,  (7,  x)  is  made  up  principally  of  large  empty  cells,  with 
pointed  ends,  whose  walls  are  marked  with  closely  set,  narrow,  transverse 
pits,  giving  them  the  appearance  of  little  ladders,  whence  they  are  called 
"  scalariform,"  or  ladder- shaped  markings.  These  empty  cells  are  known 
as  "  tracheids,"  and  tissue  composed  of  such  empty  cells,  "tracheary 
tissue."  Besides  the  tracheids,  there  are  a  few  small  cells  with  oblique 
ends,  and  with  some  granular  contents. 

The  phloem  is  composed  of  cells  similar  to  the  latter,  but  there  may 
also  be  found,  especially  in  the  stem,  other  larger  ones  (Fig.  67,  </),  whose 


PTERIDOPHYTES.  Ill 

walls   are  marked  with  shallow  depressions,   whose  bottoms  are  finely 
pitted.     These  are  the  so-called  "  sieve  tubes." 

For  microscopical  examination,  either  fresh  or  alcoholic  material  may 
be  used,  the  sections  being  mounted  in  water.  Potash  will  be  found  use- 
ful in  rendering  opaque  sections  transparent. 

The  leaves,  when  young,  are  coiled  up  (Fig.  67,  (7),  owing  to 
growth  in  the  earlier  stages  being  greater  on  the  lower  than  on 
the  upper  side.  As  the  leaf  unfolds,  the  stalk  straightens,  and 
the  upper  portion  (blade)  becomes  flat. 

The  general  structure  of  the  leaf  stalk  may  be  understood 
by  making  a  series  of  cross-sections  at  different  heights,  and 
examining  them  with  a  hand  lens.  The  arrangement  is  essen- 
tially the  same  as  in  the  stem.  The  epidermis  and  immediately 
underlying  ground  tissue  are  dark-colored,  but  the  inner  ground 
tissue  is  light-colored,  and  much  softer  than  the  corresponding 
part  of  the  stem ;  and  some  of  the  outer  cells  show  a  greenish 
color,  due  to  the  presence  of  chlorophyll. 

The  section  of  the  fibro-vascular  bundle  differs  at  different 
heights.  Near  the  base  of  the  stalk  (Fig.  D  i)  it  is  horseshoe- 
shaped;  but,  if  examined  higher  up,  it  is  found  to  divide 
(n,  in),  one  part  going  to  each  of  the  main  branches  of  the 
leaf.  These  secondary  bundles  divide  further,  forming  the 
veins  of  the  leaflets. 

The  leaflets  (J5J,  F)  are  one-sided,  the  principal  vein  running 
close  to  the  lower  edge,  and  the  others  branching  from  it,  and 
forking  as  they  approach  the  upper  margin,  which  is  deeply 
lobed,  the  lobes  being  again  divided  into  teeth.  The  leaflets 
are  very  thin  and  delicate,  with  extremely  smooth  surface, 
which  sheds  water  perfectly.  If  the  plant  is  a  large  one,  some 
of  the  leaves  will  probably  bear  spores.  The  spore-bearing 
leaves  are  at  once  distinguished  by  having  the  middle  of  each 
lobe  of  the  leaflets  folded  over  upon  the  lower  side  (F).  On 
lifting  one  of  these  flaps,  numerous  little  rounded  bodies 
(spore  cases)  are  seen,  whitish  when  young,  but  becoming 
brown  as  they  ripen.  If  a  leaf  with  ripe  spore  cases  is  placed 


112 


BOTANY. 


upon  a  piece  of  paper,  as  it  dries  the  spores  are  discharged, 
covering  the  paper  with  the  spores,  which  look  like  fine  brown 
powder. 


FIG.  G8.  —  A,  vertical  section  of  the  leaf  of  the  maiden-hair  fern,  which  has  cut 
across  a  vein  (/.&.) ,  x  150.  B,  surface  view  of  the  epidermis  from  the  lower  sur- 
face of  a  leaf.  /,  vein,  p,  breathing  pore,  x  150.  (7,  longitudinal  section  of  the 
fibro-yascular  bundle  of  the  leaf  stalk,  showing  tracheids  with  ladder-shaped 
markings,  x  150.  D,  longitudinal  section  through  the  tip  of  a  root,  x  150. 
a,  apical  cell.  PL  young  fibro-vascular  bundle.  Pb.  young  ground  tissue. 

E,  cross-section  of  the  root,  through  the  region  of  the  apical  cell  (a),  x  150. 

F,  cross-section  through  a  full-grown  root,  x  25.    r,  root  hairs.    G,  the  fibre- 
vascular  bundle  of  the  same,  x  150. 

A  microscopical  examination  of  the  leaf  stalk  shows  the  tissues  to  be 
almost  exactly  like  those  of  the  stem,  except  the  inner  ground  tissue, 
whose  cells  are  thin-walled  and  colorless  (soft  tissue  or  "parenchyma) 
instead  of  stony  tissue.  The  structure  of  the  blade  of  the  leaf,  however, 
shows  a  number  of  peculiarities.  Stripping  off  a  little  of  the  epidermis 
with  a  needle,  or  shaving  off  a  thin  slice  with  a  razor,  it  may  be  examined 
in  water,  removing  the  air  if  necessary  with  alcohol.  It  is  composed  of  a 
single  layer  of  cells,  of  very  irregular  outline,  except  where  it  overlies  a 
vein  (Fig.  68,  £,/).  Here  the  cells  are  long  and  narrow,  with  heavy 


PTEBIDOPHYTES. 


113 


walls.  The  epidermal  cells  contain  numerous  chloroplasts,  and  on  the 
under  surface  of  Jhe  leaf  breathing  pores  (stomata,  sing,  stoma),  not 
unlike  those  on  the  capsules  of  some  of  the  bryophytes.  Each  breathing 
pore  consists  of  two  special  crescent- shaped  epidermal  cells  (guard  cells), 
enclosing  a  central  opening  or  pore  communicating  with  an  air  space 
below.  They  arise  from  cells  of  the 
young  epidermis  that  divide  by  a 
longitudinal  wall,  that  separates  in  the 
middle,  leaving  the  space  between. 

By  holding  a  leaflet  between  two 
pieces  of  pith,  and  using  a  very  sharp 
razor,  cross-sections  can  be  made. 
Such  a  section  is  shown  in  Fig.  68, 
A.  The  epidermis  (e)  bounds  the 
upper  and  lower  surfaces,  and  if  a 
vein  (/.&.)  is  cut  across  its  structure 
is  found  to  be  like  that  of  the  fibro- 
vascular  bundle  of  the  leaf  stalk,  but 
much  simplified. 

The  ground  tissue  of  the  leaf  is 
composed  of  very  loose,  thin- walled 
cells,  containing  numerous  chloro- 
plasts. Between  them  are  large  and 
numerous  intercellular  spaces,  filled 
with  air,  and  communicating  with  the 
breathing  pores.  These  are  the  prin- 
cipal assimilating  cells  of  the  plant ; 
i.e.  they  are  principally  concerned  in 
the  absorption  and  decomposition  of 
carbonic  acid  from  the  atmosphere, 
and  the  manufacture  of  starch. 

The  spore  cases,  or  sporangia  (Fig. 
69),  are  at  first  little  papillae  (.4), 
arising  from  the  epidermal  cells,  from 
which  they  are  early  cut  off  by  a 
cross-wall.  In  the  upper  cell  several  walls  next  arise,  forming  a  short 
stalk,  composed  of  three  rows  of  cells,  and  an  upper  nearly  spherical  cell 
—  the  sporangium  proper.  The  latter  now  divides  by  four  walls  (_B,  (7, 
i-iv),  into  a  central  tetrahedral  cell,  and  four  outer  ones.  The  central 
cell,  whose  contents  are  much  denser  than  the  outer  ones,  divides  again 
by  walls  parallel  to  those  first  formed,  so  that  the  young  sporangium  now 


FIG.   69.  —  A, 
sporangium 


mother  cell  of  the 
of  the  maiden-hair 
fern,  *  300.  B,  young  sporangium, 
surface  view,  x  150  :  i,  from  the 
side;  n,  from  above.  C-E,  suc- 
cessive stages  in  the  development 
of  the  sporangium  seen  in  optical 
section,  x  150.  F,  nearly  ripe 
sporangium,  x  50:  i,  from  in  front  ; 
n,  from  the  side.  an.  ring,  st- 
point  of  opening.  G,  group  of  four 
spores,  x  150.  H  a  sinle 
x  300. 


a  single  spore, 


114  BOTANY. 

consists  of  a  central  cell,  surrounded  by  two  outer  layers  of  cells.  From 
the  central  cell  a  group  of  cells  is  formed  by  further  divisions  (Z>),  which 
finally  become  entirely  separated  from  each  other.  The  outer  cells  of  the 
spore  case  divide  only  by  walls,  at  right  angles  to  their  outer  surface,  so 
that  the  wall  is  never  more  than  two  cells  thick.  Later,  the  inner  of  these 
two  layers  becomes  disorganized,  so  that  the  central  mass  of  cells  floats 
free  in  the  cavity  of  the  sporangium,  which  is  now  surrounded  by  but  a 
single  layer  of  cells  (E). 

Each  of  the  central  cells  divides  into  four  spores,  precisely  as  in  the 
bryophytes.  The  young  spores  (G,  H)  are  nearly  colorless  and  are 
tetrahedral  (like  a  three-sided  pyramid)  in  form.  As  they  ripen,  chloro- 
phyll is  formed  in  them,  and  some  oil.  The  wall  becomes  differentiated 
into  three  layers,  the  outer  opaque  and  brown,  the  two  inner  more  delicate 
and  colorless. 

Running  around  the  outside  of  the  ripe  spore  case  is  a  single  row  of 
cells  (aw.),  differing  from  the  others  in  shape,  and  having  their  inner  walls 
thickened.  Near  the  bottom,  two  (sometimes  four)  of  these  cells  are 
wider  than  the  others,  and  their  walls  are  more  strongly  thickened.  It  is 
at  this  place  (st. )  that  the  spore  case  opens.  When  the  ripe  sporangium 
becomes  dry,  the  ring  of  thickened  cells  (an.)  contracts  more  strongly  than 
the  others,  and  acts  like  a  spring  pulling  the  sporangium  open  and  shaking 
out  the  spores,  which  germinate  readily  under  favorable  conditions,  and 
form  after  a  time  the  sexual  plants  (prothallia). 

The  roots  of  the  sporophyte  arise  in  large  numbers,  the 
youngest  being  always  nearest  the  growing  point  of  the  stem 
or  larger  roots  (Fig.  67,  C).  The  growing  roots  are  pointed 
at  the  end  which  is  also  light-colored,  the  older  parts  becoming 
dark  brown.  A  cross-section  of  the  older  portions  shows  a 
dark-brown  ground  tissue  with  a  central,  light-colored,  circular, 
fibre-vascular  bundle  (Fig.  68,  F).  Growing  from  its  outer 
surface  are  numerous  brown  root  hairs  (r) . 

When  magnified  the  walls  of  all  the  outer  cells  (epidermis  and  ground 
tissue)  are  found  to  be  dark-colored  but  not  very  thick,  and  the  cells  are 
usually  filled  with  starch.  There  is  a  bundle  sheath  of  much-flattened  cells 
separating  the  fibro-vascular  bundle  from  the  ground  tissue.  The  bundle 
(Fig.  68,  G)  shows  a  band  of  tracheary  tissue  in  the  centre  surrounded  by 
colorless  cells,  all  about  alike. 


PTERIDOPHYTES.  115 

All  of  the  organs  of  the  fern  grow  from  a  definite  apical  cell,  but  it  is 
difficult  to  study  except  in  the  root. 

Selecting  a  fresh,  pretty  large  root,  a  series  of  thin  longitudinal  sections 
should  be  made  either  holding  the  root  directly  in  the  fingers  or  placing 
it  between  pieces  of  pith.  In  order  to  avoid  drying  of  the  sections,  as  is 
indeed  true  in  cutting  any  delicate  tissue,  it  is  a  good  plan  to  wet  the 
blade  of  the  razor.  If  the  section  has  passed  through  the  apex,  it  will 
show  the  structure  shown  in  Figure  68,  D.  The  apical  cell  (a)  is  large  and 
distinct,  irregularly  triangular  in  outline.  It  is  really  a  triangular  pyramid 
(tetrahedron)  with  the  base  upward,  which  is  shown  by  making  a  series 
of  cross-sections  through  the  root  tip,  and  comparing  them  with  the  longi- 
tudinal sections.  The  cross-section  of  the  apical  cell  (Fig.  L)  appears  also 
triangular,  showing  all  its  faces  to  be  triangles.  Regular  series  of  seg- 
ments are  cut  off  in  succession  from  each  of  the  four  faces  of  the  apical 
cell.  These  segments  undergo  regular  divisions  also,  so  that  very  early 
a  differentiation  of  the  tissues  is  evident,  and  the  three  tissue  systems 
(epidermal,  ground,  and  fibro-vascular)  may  be  traced  almost  to  the  apex 
of  the  root  (68,  D).  From  the  outer  series  of  segments  is  derived  the 
peculiar  structure  (root  cap)  covering  the  delicate  growing  point  and  pro- 
tecting it  from  injury. 

The  apices  of  the  stem  and  leaves,  being  otherwise  protected,  develop 
segments  only  from  the  sides  of  the  apical  cell,  the  outer  face  never 
having  segments  cut  off  from  it. 


CHAPTER  XIII. 

CLASSIFICATION    OF   THE   PTERIDOFHYTES. 

THERE  are  three  well-marked  classes  of  the  Pteridophytes : 
the  ferns  (Filicince)',  horse-tails  (Equisetince);  and  the  club 
mosses  (Lycopodince). 

CLASS  I. — FERNS   (FilicinGe). 

The  ferns  constitute  by  far  the  greater  number  of  pterido- 
phytes,  and  their  general  structure  corresponds  with  that  of 
the  maiden-hair  fern  described.  There  are  three  orders,  of 
which  two,  the  true  ferns  (Filices)  and  the  adder-tongues 
(Ophioglossacece)  j  are  represented  in  the  United  States.  A 
third  order,  intermediate  in  some  respects  between  these  two, 
and  called  the  ringless  ferns  (Marattiacece) ,  has  no  representa- 
tives within  our  territory. 

The  classification  is  at  present  based  largely  upon  the  char- 
acters of  the  sporophyte,  the  sexual  plants  being  still  very 
imperfectly  known  in  many  forms. 

The  adder-tongues  (Ophioglossacece)  are  mostly  plants  of 
rather  small  size,  ranging  from  about  ten  to  fifty  centimetres 
in  height.  There  are  two  genera  in  the  United  States,  the 
true  adder-tongues  (OpMoglossum)  and  the  grape  ferns  (Botry- 
chium).  They  send  up  but  one  leaf  each  year,  and  this  in 
fruiting  specimens  (Fig.  70,  A)  is  divided  into  two  portions, 
the  spore  bearing  (x)  and  the  green  vegetative  part.  In  Botry- 
chium  the  leaves  are  more  or  less  deeply  divided,  and  the 
sporangia  distinct  (Fig.  71,  -B).  In  Ophioglossum  the  sterile 
division  of  the  leaf  is  usually  smooth  and  undivided,  and  the 
116 


CLASSIFICATION  OF  THE  PTERIDOPHYTES.       117 

spore-bearing  division  forms  a  sort  of  spike,  and  the  sporangia 
are  much  less  distinct.  The  sporangia  in  both  differ  essen- 
tially from  those  of  the  true  ferns  in  not  being  derived  from 
a  single  epidermal  cell,  but  are  developed  in  part  from  the 
ground  tissue  of  the  leaf. 


FIG.  70.  —  Forms  of  ferns.  A,  grape  fern  (Botrychium) ,  x  l/2.  x,  fertile  part 
of  the  leaf.  B,  sporangia  of  Botrychium,  x  3.  C,  flowering  fern  (Osmunda). 
x,  spore-bearing  leaflets,  x  %.  D,  a  sporangium  of  Osmunda,  x  25.  r,  ring. 
E,  Polypodium,  x  l.  F,  brake  (Pteris),  x  1.  G,  shield  fern  (Aspidium),  x  2. 
H,  spleen-wort  (Asplenium),  x  2.  /,  ostrich  fern  (Onoclea),  x  1.  J,  the 
same,  with  the  incurved  edges  of  the  leaflet  partially  raised  so  as  to  show  the 
masses  of  sporangia  beneath,  x  2. 


In  the  true  ferns  (Filices),  the  sporangia  resemble  those 
already  described,  arising  in  all  (unless  possibly  Osmunda) 
from  a  single  epidermal  cell. 

One  group,  the  water  ferns  (Rhizocarpece) ,  produce  two 
kinds  of  spores,  large  and  small.  The  former  produce  male, 
the  latter  female  prothallia.  In  both  cases  the  prothallium  is 


118 


BOTANY. 


small,  and  often  scarcely  protrudes  beyond  the  spore,  and  may 
be  reduced  to  a  single  archegonium  or  antheridium  (Fig.  71, 
.B,  C)  with  only  one  or  two  cells  representing  the  vegetative 
cells  of  the  prothallium  (v).  The  water  ferns  are  all  aquatic 
or  semi-aquatic  plants,  few  in  number  and  scarce  or  local  in 

their  distribution.  The  com- 
monest are  those  of  the 
genus  Marsilia  (Fig.  71,  A), 
looking  like  a  four-leaved 
clover.  Others  (Salvinia, 
Azolla)  are  floating  forms 
(Fig.  71,  D). 

Of  the  true  ferns  there  are 
a  number  of  families  distin- 
guished mainly  by  the  posi- 
tion of  the  sporangia,  as  well 
as  by  some  differences  in 
their  structure.  Of  our  com- 
mon ferns,  those  differing 
most  widely  from  the  types 
are  the  flowering  ferns  (Os- 
munda),  shown  in  Figure  70, 
(7,  D.  In  these  the  sporan- 


FIG.  71.  —  A,  Marsilia,  one  of  the  Rhizo- 
carpesR  (after  Underwood),  sp.  the 
"fruits"  containing  the  sporangia. 
B,  a  small  spore  of  Pilularia,  with 
the  ripe  antheridium  protruding, 
x  180.  C,  male  prothallium  removed 
from  the  spore,  x  180.  D,  Azolla 
(after  Sprague),  x  1. 


gia  are  large  and  the  ring  (?*) 
rudimentary.  The  leaflets 
bearing  the  sporangia  are 
more  or  less  contracted  and 
covered  completely  with  the 
sporangia,  sometimes  all  the  leaflets  of  the  spore-bearing  leaf 
being  thus  changed,  sometimes  only  a  few  of  them,  as  in  the 
species  figured. 

Our  other  common  ferns  have  the  sporangia  in  groups  (sori, 
sing,  soms)  on  the  backs  of  the  leaves.  These  sori  are  of 
different  shape  in  different  genera,  and  are  usually  protected 
by  a  delicate  membranous  covering  (indusium).  Illustra- 


CLASSIFICATION   OF  THE  PTEEIDOPHYTES.       119 


tions  of  some  of  the  commonest  genera  are  shown  in  Figure 
70,  E,  J. 

CLASS  II.  —  HORSE-TAILS   (Equisetince)  . 

The  second  class  of  the  pteridophytes  includes  the  horse- 
tails (Equisetince)  of  which  all  living  forms  belong  to  a  single 


p.- 


FIG.  72.—  A,  spore-bearing  stem  of  the  field  horse-tail  (Equisetum),  x  1.  x, 
the  spore-bearing  cone.  JB,  sterile  stem  of  the  same,  x  %..  C,  underground 
stem,  with  tubers  (o),x%.  D,  cross-section  of  an  aerial  stem,  x  5.  /.&. 
fibro-vascular  bundle.  E,  a  single  fibre-vascular  bundle,  x  150.  tr.  vessels. 
F,  a  single  leaf  from  the  cone,  x  5.  G,  the  same  cut  lengthwise,  through  a 
spore  sac  (sp.),  x  5.  jj,  a  spore,  x  50.  /,  the  same,  moistened  so  that  the 
elaters  are  coiled  up,  x  150.  J,  a  male  prothallium,  x  50.  an.  an  antheridium. 
K,  spermatozoids,  x  300. 

genus  (Equisetum) .  Formerly  they  were  much  more  numerous 
than  at  present,  remains  of  many  different  forms  being  espe- 
cially abundant  in  the  coal  formations. 


120  BOTANY. 

One  of  the  commonest  forms  is  the  field  horse-tail  (Equi- 
setum  arvense),  a  very  abundant  and  widely  distributed  species. 
It  grows  in  low,  moist  ground,  and  is  often  found  in  great 
abundance  growing  in  the  sand  or  gravel  used  as  "ballast"  for 
railway  tracks. 

The  plant  sends  up  branches  of  two  kinds  from  a  creeping 
underground  stem  that  may  reach  a  length  of  a  metre  or  more. 
This  stem  (Fig.  72,  (7)  is  distinctly  jointed,  bearing  at  each 
joint  a  toothed  sheath,  best  seen  in  the  younger  portions,  as 
they  are  apt  to  be  destroyed  in  the  older  parts.  Sometimes 
attached  to  this  are  small  tubers  (o)  which  are  much-short- 
ened branches  and  under  favorable  circumstances  give  rise  to 
new  stems.  They  have  a  hard,  brown  rind,  and  are  composed 
within  mainly  of  a  firm,  white  tissue,  filled  with  starch. 

The  surface  of  the  stem  is  marked  with  furrows,  and  a  sec- 
tion across  it  shows  that  corresponding  to  these  are  as  many 
large  air  spaces  that  traverse  the  stem  from  joint  to  joint. 
From  the  joints  numerous  roots,  quite  like  those  of  the  ferns, 
arise. 

If  the  stem  is  dug  up  in  the  late  fall  or  winter,  numerous 
short  branches  of  a  lighter  color  will  be  found  growing  from 
the  joints.  These  later  grow  up  above  ground  into  branches 
of  two  sorts.  Those  produced  first  (Fig.  72,  J.),  in  April  or 
May,  are  stouter  than  the  others,  and  nearly  destitute  of  chlo- 
rophyll. They  are  usually  twenty  to  thirty  centimetres  in 
height,  of  a  light  reddish  brown  color,  and,  like  all  the  stems, 
distinctly  jointed.  The  sheaths  about  the  joints  (L)  are  much 
larger  than  in  the  others,  and  have  from  ten  to  twelve  large 
black  teeth  at  the  top.  These  sheaths  are  the  leaves.  At  the 
top  of  the  branch  the  joints  are  very  close  together,  and  the 
leaves  of  different  form,  and  closely  set  so  as  to  form  a  com- 
pact cone  (a;). 

A  cross-section  of  the  stem  (D)  shows  much  the  same  struc- 
ture as  the  underground  stem,  but  the  number  of  air  spaces  is 
larger,  and  in  addition  there  is  a  large  central  cavity.  The 


CLASSIFICATION   OF  THE  PTERIDOPHYTES.       121 

fibro- vascular  bundles  (/&.)  are  arranged  in  a  circle,  alternating 
with  the  air  channels,  and  each  one  has  running  through  it  a 
small  air  passage. 

The  cone  at  the  top  of  the  branch  is  made  up  of  closely  set, 
shield-shaped  leaves,  which  are  mostly  six-sided,  on  account  of 
the  pressure.  These  leaves  (F,  G)  have  short  stalks,  and  are 
arranged  in  circles  about  the  stem.  Each  one  has  a  number 
of  spore  cases  hanging  down  from  the  edge,  and  opening  by  a 
cleft  on  the  inner  side  (G,  sp.}.  They  are  filled  with  a  mass 
of  greenish  spores  that  shake  out  at  the  slightest  jar  when 
ripe. 

The  sterile  branches  (B)  are  more  slender  than  the  spore- 
bearing  ones,  and  the  sheaths  shorter.  Surrounding  the  joints, 
apparently  just  below  the  sheaths,  but  really  breaking  through 
their  bases,  are  circles  of  slender  branches  resembling  the  main 
branch,  but  more  slender.  The  sterile  branches  grow  to  a 
height  of  forty  to  fifty  centimetres,  and  from  their  bushy  form 
the  popular  name  of  the  plant,  "horse-tail,"  is  taken.  The 
surface  of  the  plant  is  hard  and  rough,  due  to  the  presence  of 
great  quantities  of  flint  in  the  epidermis,  —  a  peculiarity  com- 
mon to  all  the  species. 

The  stem  is  mainly  composed  of  large,  thin-walled  cells,  becoming 
smaller  as  they  approach  the  epidermis.  The  outer  cells  of  the  ground 
tissue  in  the  green  branches  contain  chlorophyll,  and  the  walls  of  some  of 
them  are  thickened.  The  fibro- vascular  bundles  differ  entirely  from  those 
of  the  ferns.  Each  bundle  is  nearly  triangular  in  section  (£"),  with  the 
point  inward,  and  the  inner  end  occupied  by  a  large  air  space.  The 
tracheary  tissue  is  only  slightly  developed,  being  represented  by  a  few 
vessels 1  (tr)  at  the  outer  angles  of  the  bundle,  and  one  or  two  smaller  ones 
close  to  the  air  channel.  The  rest  of  the  bundle  is  made  up  of  nearly 
uniform,  rather  thin- walled,  colorless  cells,  some  of  which,  however,  are 
larger,  and  have  perforated  cross-walls,  representing  the  sieve  tubes  of 

1  A  vessel  differs  from  a  tracheid  in  being  composed  of  several  cells 
placed  end  to  end,  the  partitions  being  wholly  or  partially  absorbed,  so  as 
to  throw  the  cells  into  close  communication. 


122  BOTANY. 

the  fern  bundle.  There  is  no  individual  bundle  sheath,  but  the  whole 
circle  of  bundles  has  a  common  outer  sheath. 

The  epidermis  is  composed  of  elongated  cells  whose  walls  present  a 
peculiar  beaded  appearance,  due  to  the  deposition  of  flint  within  them. 
The  breathing  pores  are  arranged  in  vertical  lines,  and  resemble  in  general 
appearance  those  of  the  ferns,  though  differing  in  some  minor  details. 
Like  the  other  epidermal  cells  the  guard  cells  have  heavy  deposits  of  flint, 
which  here  are  in  the  form  of  thick  transverse  bars. 

The  spore  cases  have  thin  walls  whose  cells,  shortly  before  maturity, 
develop  thickenings  upon  their  walls,  which  have  to  do  with  the  opening 
of  the  spore  case.  The  spores  (Z7,  7)  are  round  cells  containing  much 
chlorophyll  and  provided  with  four  peculiar  appendages  called  elaters. 
The  elaters  are  extremely  sensitive  to  changes  in  moisture,  coiling  up 
tightly  when  moistened  (7),  but  quickly  springing  out  again  when  dry  (77). 
By  dusting  a  few  dry  spores  upon  a  slide,  and  putting  it  under  the  micro- 
scope without  any  water,  the  movement  may  be  easily  examined.  Lightly 
breathing  upon  them  will  cause  the  elaters  to  contract,  but  in  a  moment, 
as  soon  as  the  moisture  of  the  breath  has  evaporated,  they  will  uncoil 
with  a  quick  jerk,  causing  the  spores  to  move  about  considerably. 

The  fresh  spores  begin  to  germinate  within  about  twenty-four  hours, 
and  the  early  stages,  which  closely  resemble  those  of  the  ferns,  may  be 
easily  followed  by  sowing  the  spores  in  water.  With  care  it  is  possible 
to  get  the  mature  prothallia,  which  should  be  treated  as  described  for  the 
fern  prothallia.  Under  favorable  conditions,  the  first  antheridia  are  ripe 
in  about  five  weeks  ;  the  archegonia,  which  are  borne  on  separate  plants, 
a  few  weeks  later.  The  antheridia  (Fig.  72,  J,  an.)  are  larger  than  those 
of  the  ferns,  and  the  spermatozoids  (K)  are  thicker  and  with  fewer  coils, 
but  otherwise  much  like  fern  spermatozoids. 

The  archegonia  have  a  shorter  neck  than  those  of  the  ferns,  and  the 
neck  is  straight. 

Both  male  and  female  prothallia  are  much  branched  and  very  irregular 
in  shape. 

There  are  a  number  of  common  species  of  Equisetum.  Some 
of  them,  like  the  common  scouring  rush  (E.  hiemale),  are  un- 
branched,  and  the  spores  borne  at  the  top  of  ordinary  green 
branches ;  others  have  all  the  stems  branching  like  the  sterile 
stems  of  the  field  horse-tail,  but  produce  a  spore-bearing  cone 
at  the  top  of  some  of  them. 


CLASSIFICATION  OF  THE  PTERIDOPHYTES.       123 

CLASS  III.  —  THE  CLUB  MOSSES  (Lycopodince) . 

The  last  class  of  the  pteridophytes  includes  the  ground 
pines,  club  mosses,  etc.,  and  among  cultivated  plants  numerous 
species  of  the  smaller  club  mosses  (Selaginelld). 

Two  orders  are  generally  recognized,  although  there  is  some 
doubt  as  to  the  relationship  of  the  members  of  the  second 
order.  The  first  order,  the  larger  club  mosses  (Lycopodiacece) 
is  represented  in  the  northern  states  by  a  single  genus  (Lyco- 
podium),  of  which  the  common  ground  pine  (L.  dendroideum) 
(Fig.  73)  is  a  familiar  species.  The  plant  grows  in  the  ever- 
green forests  of  the  northern  United  States  as  well  as  in  the 
mountains  further  south,  and  in  the  larger  northern  cities  is 
often  sold  in  large  quantities  at  the  holidays  for  decorating. 
It  sends  up  from  a  creeping,  woody,  subterranean  stem,  numer- 
ous smaller  stems  which  branch  extensively,  and  are  thickly 
set  with  small  moss-like  leaves,  the  whole  looking  much  like 
a  little  tree.  At  the  ends  of  some  of  the  branches  are  small 
cones  (A,  x,  B)  composed  of  closely  overlapping,  scale-like 
leaves,  much  as  in  a  fir  cone.  Near  the  base,  on  the  inner 
surface  of  each  of  these  scales,  is  a  kidney-shaped  capsule 
(C,  sp.)  opening  by  a  cleft  along  the  upper  edge  and  filled 
with  a  mass  of  fine  yellow  powder.  These  capsules  are  the 
spore  cases. 

The  bases  of  the  upright  stems  are  almost  bare,  but  become 
covered  with  leaves  higher  up.  The  leaves  are  in  shape  like 
those  of  a  moss,  but  are  thicker.  The  spore-bearing  leaves  are 
broader  and  when  slightly  magnified  show  a  toothed  margin. 

The  stem  is  traversed  by  a  central  nbro-vascular  cylinder 
that  separates  easily  from  the  surrounding  tissue,  owing  to  the 
rupture  of  the  cells  of  the  bundle  sheath,  this  being  particu- 
larly frequent  in  dried  specimens.  When  slightly  magnified 
the  arrangement  of  the  tissues  may  be  seen  (Fig.  73,  E). 
Within  the  epidermis  is  a  mass  of  ground  tissue  of  firm, 
woody  texture  surrounding  the  central  oval  or  circular  fibro- 


124 


BOTANY. 


vascular  cylinder.    This  shows  a  number  of  white  bars  (xylem) 
surrounded  by  a  more  delicate  tissue  (phloem) . 

On  magnifying  the  section  more  strongly,  the  cells  of  the  ground  tissue 
(G)  are  seen  to  be  oval  in  outline,  with  thick  striated  walls  and  small  in- 


Fia.  73.  —  A,  a  club  moss  (Lycopodium) ,  x  y3.  x,  cone,  r,  root.  B,  a  cone, 
x  1.  (7,  single  scale  with  sporangium  (sp.).  D,  spores:  i,  from  above  ;  u, 
from  below,  x  325.  E,  cross  section  of  stem,  x  8.  /.&.  fibro- vascular  bundle. 
F,  portion  of  the  nbro-vascular  bundle,  x  150.  G,  cells  of  the  ground  tissue, 
x  150. 

tercellular  spaces.     Examined  in  longitudinal  sections  they  are  long  and 
pointed,  belonging  to  the  class  of  cells  known  as  "  fibres." 

The  xylem  (JP7,  xy.)  of  the  fibro- vascular  bundle  is  composed  of  tra- 
cheids,  much  like  those  of  the  ferns  ;  the  phloem  is  composed  of  narrow 
cells,  pretty  much  all  alike. 


CLASSIFICATION   OF  THE  PTERIDOPHYTES.       125 


The  spores  (D)  are  destitute  of  chlorophyll  and  have  upon  the  outside 
a  network  of  ridges,  except  on  one  side  where  three  straight  lines  con- 
verge, the  spore  being  slightly  flattened  between  them. 

Almost  nothing  is  known  of  the  prothallia  of  our  native  species. 

The  second  order  (Ligulatce)  is  represented  by  two  very 
distinct  families  :  the  smaller  club  mosses  (Selaginellece)  and 


FIG.  74. —  A,  one  of  the  smaller  club  mosses  (Selaginella) .  sp.  spore-bearing 
branch,  x  2.  B,  part  of  a  stem,  sending  down  naked  rooting  branches  (r), 
x  1.  C,  longitudinal  section  of  a  spike,  with  a  single  macrosporangium 
at  the  base;  the  others,  microsporangia,  x  3.  D,  a  scale  and  microspo- 
rangium,  x  5.  E,  young  microsporangium,  x  150.  The  shaded  cells  are  the 
spore  mother  cells.  F,  a  young  macrospore,  x  150.  G,  section  of  the  stem, 
x  50.  H,  a  single  fibre-vascular  bundle,  x  150.  /,  vertical  section  of  the 
female  prothallium  of  Selaginella,  x  50.  ar.  archegonium.  J,  section  of  an 
open  archegonium,  x  300.  o,  the  egg  cell.  K,  microspore,  with  the  contained 
male  prothallium,  x  300.  x,  vegetative  cell.  sp.  sperm  cells.  L,  young 
plant,  with  the  attached  macrospore,  x  6.  r,  the  first  root.  I,  the  first  leaves. 

the  quill-worts  (Isoetece).  Of  the  former  the  majority  are 
tropical,  but  are  common  in  greenhouses  where  they  are  prized 
for  their  delicate  moss-like  foliage  (Fig.  74,  A) . 


126  BOTANY. 

The  leaves  in  most  species  are  like  those  of  the  larger  club 
mosses,  but  more  delicate.  They  are  arranged  in  four  rows  on 
the  upper  side  of  the  stem,  two  being  larger  than  the  others. 
The  smaller  branches  grow  out  sideways  so  that  the  whole 
branch  appears  flattened,  reminding  one  of  the  habit  of  the 
higher  liverworts.  Special  leafless  branches  (B,  r)  often  grow 
downward  from  the  lower  side  of  the  main  branches,  and  on 
touching  the  ground  develop  roots  which  fork  regularly. 

The  sporangia  are  much  like  those  of  the  ground  pines,  and 
produced  singly  at  the  bases  of  scale  leaves  arranged  in  a  spike 
or  cone  (A,  sp.),  but  two  kinds  of  spores,  large  and  small,  are 
formed.  In  the  species  figured  the  lower  sporangium  produces 
four  large  spores  (macrospores)  ;  the  others,  numerous  small 
spores  (microspores). 

Even  before  the  spores  are  ripe  the  development  of  the 
prothalliuni  begins,  and  this  is  significant,  as  it  shows  an 
undoubted  relationship  between  these  plants  and  the  lowest 
of  the  seed  plants,  as  we  shall  see  when  we  study  that  group. 

If  ripe  spores  can  be  obtained  by  sowing  them  upon  moist  earth,  the 
young  plants  will  appear  in  about  a  month.  The  microspore  (Fig.  74,  K) 
produces  a  prothallium  not  unlike  that  of  some  of  the  water  ferns,  there 
being  a  single  vegetative  cell  (#),  and  the  rest  of  the  prothallium  forming 
a  single  antheridium.  The  spermatozoids  are  excessively  small,  and 
resemble  those  of  the  bryophytes. 

The  macrospore  divides  into  two  cells,  a  large  lower  one,  and  a  smaller 
upper  one.  The  latter  gives  rise  to  a  flat  disc  of  cells  producing  a  number 
of  small  archegonia  of  simple  structure  (Fig.  74,  7,  J).  The  lower  cell 
produces  later  a  tissue  that  serves  to  nourish  the  young  embryo. 

The  development  of  the  embryo  recalls  in  some  particulars  that  of  the 
seed  plants,  and  this  in  connection  with  the  peculiarities  of  the  sporangia 
warrants  us  in  regarding  the  Ligulatce  as  the  highest  of  existing  pterido- 
phytes,  and  to  a  certain  extent  connecting  them  with  the  lowest  of  the 
spermaphytes. 

Resembling  the  smaller  club  mosses  in  their  development, 
but  differing  in  some  important  points,  are  the  quill-worts 
(Isoetece) .  They  are  mostly  aquatic  forms,  growing  partially 


CLASSIFICATION  OF  THE  PTEEIDOPHYTES.       127 

or  completely  submerged,  and  look  like  grasses  or  rushes. 
They  vary  from  a  few  centimetres  to  half  a  metre  in  height. 
The  stem  is  very  short,  and  the  long  cylindrical  leaves  closely 
crowded  together.  The  leaves  which  are  narrow  above  are 
widely  expanded  and  overlapping  at  the  base.  The  spores  are 
of  two  kinds,  as  in  Selaginella,  but  the  macrosporangia  contain 
numerous  macrospores.  The  very  large  sporangia  (3fj  sp.) 
are  in  cavities  at  the  bases  of  the  leaves,  and  above  each 
sporangium  is  a  little  pointed  outgrowth  (ligula),  which  is  also 
found  in  the  leaves  of  Selaginella. 

The  quill-worts  are  not  common  plants,  and  owing  to  their 
habits  of  growth  and  resemblance  to  other  plants,  are  likely 
to  be  overlooked  unless  careful  search  is  made. 


CHAPTER   XIV. 


SUB-KINGDOM  VI. 
SPERMAPHYTES  :    PH^ENOGAMS. 

THE  last  and  highest  great  division  of  the  vegetable  king- 
dom has  been  named  Spermaphyta,  "  seed  plants,"  from  the  fact 
that  the  structures  known  as  seeds  are  peculiar  to  them.  They 
are  also  commonly  called  flowering  plants,  though  this  name 
might  be  also  appropriately  given  to  certain  of  the  higher 
pteridophytes. 

In  the  seed  plants  the  macrosporangia  remain  attached  to 
the  parent  plant,  in  nearly  all  cases,  until  the  archegonia  are 
fertilized  and  the  embryo  plant  formed.  The  outer  walls  of 
the  sporangium  now  become  hard,  and  the  whole  falls  off  as 
a  seed. 

In  the  higher  spermaphytes  the  spore-bearing  leaves  (sporo- 
phylls)  become  much  modified,  and  receive  special  names, 
those  bearing  the  microspores  being  commonly  known  as  sta- 
mens ;  those  bearing  the  macrospores,  carpels  or  carpophylls. 
The  macrosporangia  are  also  ordinarily  known  as  "  ovules,"  a 
name  given  before  it  was  known  that  these  were  the  same  as 
the  macrosporangia  of  the  higher  pteridophytes. 

In  addition  to  the  spore-bearing  leaves,  those  surrounding 
them  may  be  much  changed  in  form  and  brilliantly  colored, 
forming,  with  the  enclosed  sporophylls,  the  "flower"  of  the 
higher  spermaphytes. 

As  might  be  expected,  the  tissues  of  the  higher  sperma- 
phytes  are  the  most  highly  developed  of  all  plants,  though 

128 


SPEBMAPBYTES :  PH^ENOGAMS.  129 

some  of  them  are  very  simple.  The  plants  vary  extremely  in 
size,  the  smallest  being  little  floating  plants,  less  than  a  milli- 
metre in  diameter,  while  others  are  gigantic  trees,  a  hundred 
metres  and  more  in  height. 

There  are  two  classes  of  the  spermaphytes :  I.,  the  Gym- 
nosperms,  or  naked-seeded  ones,  in  which  the  ovules  (macrospo- 
rangia)  are  borne  upon  open  carpophylls ;  and  II.,  Angiosperms, 
covered-seeded  plants,  in  which  the  carpophylls  form  a  closed 
cavity  (ovary)  containing  the  ovules. 

CLASS  I.  —  GYMNOSPERMS  (Gymnospermce) . 

The  most  familiar  of  these  plants  are  the  common  ever- 
green trees  (conifers),  pines,  spruces,  cedars,  etc.  A  care- 
ful study  of  one  of  these  will  give  a  good  idea  of  the  most 
important  characteristics  of  the  class,  and  one  of  the  best 
for  this  purpose  is  the  Scotch  pine  (Pinus  sylvestris),  which, 
though  a  native  of  Europe,  is  not  infrequently  met  with 
in  cultivation  in  America.  If  this  species  cannot  be  had 
by  the  student,  other  pines,  or  indeed  almost  any  other  conifer, 
will  answer.  The  Scotch  pine  is  a  tree  of  moderate  size,  sym- 
metrical in  growth  when  young,  with  a  central  main  shaft, 
and  circles  of  branches  at  regular  intervals ;  but  as  it  grows 
older  its  growth  becomes  irregular,  and  the  crown  is  divided 
into  several  main  branches.1  The  trunk  and  branches  are 
covered  with  a  rough,  scaly  bark  of  a  reddish  brown  color, 
where  it  is  exposed  by  the  scaling  off  of  the  outer  layers. 
Covering  the  younger  branches,  but  becoming  thinner  on  the 
older  ones,  are  numerous  needle-shaped  leaves.  These  are  in 
pairs,  and  the  base  of  each  pair  is  surrounded  by  several  dry, 
blackish  scales.  Each  pair  of  leaves  is  really  attached  to  a 
very  short  side  branch,  but  this  is  so  short  as  to  make  the 

1  In  most  conifers  the  symmetrical  form  of  the  young  tree  is  maintained 
as  long  as  the  tree  lives. 


130  BOTANY. 

leaves  appear  to  grow  directly  from  the  main  branch.  Each 
leaf  is  about  ten  centimetres  in  length  and  two  millimetres 
broad.  Where  the  leaves  are  in  contact  they  are  flattened, 
but  the  outer  side  is  rounded,  so  that  a  cross-section  is  nearly 
semicircular  in  outline.  With  a  lens  it  is  seen  that  there  are 
five  longitudinal  lines  upon  the  surface  of  the  leaf,  and  careful 
examination  shows  rows  of  small  dots  corresponding  to  these. 
These  dots  are  the  breathing  pores.  If  a  cross-section  is  even 
slightly  magnified  it  shows  three  distinct  parts,  —  a  whitish 
outer  border,  a  bright  green  zone,  and  a  central  oval,  colorless 
area,  in  which,  with  a  little  care,  may  be  seen  the  sections 
of  two  fibro-vascular  bundles.  In  the  green  zone  are 
sometimes  to  be  seen  colorless  spots,  sections  of  resin  ducts, 
containing  the  resin  so  characteristic  of  the  tissues  of  the 
conifers. 

The  general  structure  of  the  stem  may  be  understood  by 
making  a  series  of  cross-sections  through  branches  of  different 
ages.  In  all,  three  regions  are  distinguishable ;  viz.,  an  outer 
region  (bark  or  cortex)  (Fig.  76,  A,  c),  composed  in  part  of 
green  cells,  and,  if  the  section  has  been  made  with  a  sharp 
knife,  showing  a  circle  of  little  openings,  from  each  of  which 
oozes  a  clear  drop  of  resin.  These  are  large  resin  ducts  (?•). 
The  centre  is  occupied  by  a  soft  white  tissue  (pith),  and  the 
space  between  the  pith  and  bark  is  filled  by  a  mass  of  woody 
tissue.  Traversing  the  wood  are  numerous  radiating  lines, 
some  of  which  run  from  the  bark  to  the  pith,  others  only  part 
way.  These  are  called  the  medullary  rays.  While  in  sections 
from  branches  of  any  age  these  three  regions  are  recognizable, 
their  relative  size  varies  extremely.  In  a  section  of  a  twig  of 
the  present  year  the  bark  and  pith  make  up  a  considerable 
part  of  the  section ;  but  as  older  branches  are  examined,  we 
find  a  rapid  increase  in  the  quantity  of  wood,  while  the  thick- 
ness of  the  bark  increases  but  slowly,  and  the  pith  scarcely 
at  all.  In  the  wood,  too,  each  year's  growth  is  marked  by  a 
distinct  ring  (A  i,  n).  As  the  branches  grow  in  diameter 


SPEBMAPHYTES :  PH^NOGAMS.  131 

the  outer  bark  becomes  split  and  irregular,  and  portions  die, 
becoming  brown  and  hard. 

The  tree  has  a  very  perfect  root  system,  but  different  from 
that  of  any  pteridophytes.  The  first  root  of  the  embryo  per- 
sists as  the  main  or  "  tap "  root  of  the  full-grown  tree,  and 
from  it  branch  off  the  secondary  roots,  which  in  turn  give  rise 
to  others. 

The  sporangia  are  borne  on  special  scale-like  leaves,  and 
arranged  very  much  as  in  certain  pteridophytes,  notably  the 
club  mosses ;  but  instead  of  large  and  small  spores  being  pro- 
duced near  together,  the  two  kinds  are  borne  on  special 
branches,  or  even  on  distinct  trees  (e.g.  red  cedar).  In  the 
Scotch  pine  the  microspores  are  ripe  about  the  end  of  May. 
The  leaves  bearing  them  are  aggregated  in  small  cones  ("flow- 
ers"), crowded  about  the  base  of  a  growing  shoot  terminating 
the  branches  (Fig.  77,  A  $).  The  individual  leaves  (sporo- 
phylls)  are  nearly  triangular  in  shape,  and  attached  by  the 
smaller  end.  On  the  lower  side  of  each  are  borne  two  spo- 
rangia (pollen  sacs)  (<7,  sp.)9  opening  by  a  longitudinal  slit,  and 
filled  with  innumerable  yellow  microspores  (pollen  spores), 
which  fall  out  as  a  shower  of  yellow  dust  if  the  branch  is 
shaken. 

The  macrosporangia  (ovules)  are  borne  on  similar  leaves, 
known  as  carpels,  and,  like  the  pollen  sacs,  borne  in  pairs,  but 
on  the  upper  side  of  the  sporophyll  instead  of  the  lower. 
The  female  flowers  appear  when  the  pollen  is  ripe.  The  leaves 
of  which  they  are  composed  are  thicker  than  those  of  the  male 
flowers,  and  of  a  pinkish  color.  At  the  base  on  the  upper  side 
are  borne  the  two  ovules  (macrosporangia)  (Fig.  77,  E,  o),  and 
running  through  the  centre  is  a  ridge  that  ends  in  a  little  spine 
or  point. 

The  ovule-bearing  leaf  has  on  the  back  a  scale  with  fringed 
edge  (Fj  sc.),  quite  conspicuous  when  the  flower  is  young,  but 
scarcely  to  be  detected  in  the  older  cone.  From  the  female 
flower  is  developed  the  cone  (Fig.  75,  A),  but  the  process  is  a 


132 


BOTANY. 


slow  one,  occupying  two  years.  Shortly  after  the  pollen  is 
shed,  the  female  flowers,  which  are  at  first  upright,  bend  down- 
ward, and  assume  a  brownish  color,  growing  considerably  in 
size  for  a  short  time,  and  then  ceasing  to  grow  for  several 
months. 


FIG.  75.  —  Scotch  pine  (Pinus  sylvestris).  A,  a  ripe  cone,  x  %.  B,  a  year-old 
cone,  x  1.  C,  longitudinal  section  of  B.  D,  a  single  scale  of  B,  showing 
the  sporangia  (ovules)  (o),  x  2.  E,  a  scale  from  a  ripe  cone,  with  the  seeds 
(s),  x  */2.  f\  longitudinal  section  of  a  ripe  seed,  x  3.  em.  the  embryo.  G,  a 
germinating  seed,  x  2.  r,  the  primary  root.  H,  longitudinal  section  through 
G,  showing  the  first  leaves  of  the  young  plant  still  surrounded  by  the  endo- 
sperm, x  4.  it  an  older  plant  with  the  leaves  (0  withdrawing  from  the  seed 
coats,  x  4.  Jt  upper  part  of  a  young  plant,  showing  the  circle  of  primary 
leaves  (cotyledons),  x  1.  K,  section  of  the  same,  x  2.  6,  the  terminal  bud. 
L,  cross-section  of  the  stem  of  the  young  plant,  x  25.  /&.  a  fibre-vascular 
bundle.  M,  cross-section  of  the  root,  x  25.  x,  wood.  ph.  bast,  of  the  fibro- 
vascular  bundle. 

In  Figure  75,  jB,  is  shown  such  a  flower  as  it  appears  in  the 
winter  and  early  spring  following.  The  leaves  are  thick  and 
fleshy,  closely  pressed  together,  as  is  seen  by  dividing  the 
flower  lengthwise,  and  each  leaf  ends  in  a  long  point  (D). 
The  ovules  are  still  very  small.  As  the  growth  of  the  tree  is 


SPEEMAPH YTES  :   PH^NOGAMS.  133 

resumed  in  the  spring,  the  flower  (cone)  increases  rapidly  in 
size  and  becomes  decidedly  green  in  color,  the  ovules  increas- 
ing also  very  much  in  size.  If  a  scale  from  such  a  cone  is 
examined  about  the  first  of  June,  the  ovules  will  probably 
be  nearly  full-grown,  oval,  whitish  bodies  two  to  three  milli- 
metres in  length.  A  careful  longitudinal  section  of  the  scale 
through  the  ovule  will  show  the  general  structure.  Such  a 
section  is  shown  in  Figure  77,  G.  Comparing  this  with  the 
sporangia  of  the  pteridophytes,  the  first  difference  that  strikes 
us  is  the  presence  of  an  outer  coat  or  integument  (in.)9  which 
is  absent  in  the  latter.  The  single  macrospore  (sp.)  is  very 
large  and  does  not  lie  free  in  the  cavity  of  the  sporangium, 
but  is  in  close  contact  with  its  wall.  It  is  filled  with  a  color- 
less tissue,  the  prothallium,  and  if  mature,  with  care  it  is 
possible  to  see,  even  with  a  hand  lens,  two  or  more  denser 
oval  bodies  (ar.),  the  egg  cells  of  the  archegonia,  which  here 
are  very  large.  The  integument  is  not  entirely  closed  at  the 
top,  but  leaves  a  little  opening  through  which  the  pollen  spores 
entered  when  the  flower  was  first  formed. 

After  the  archegonia  are  fertilized  the  outer  parts  of  the 
ovule  become  hard  and  brown,  and  serve  to  protect  the  embryo 
plant,  which  reaches  a  considerable  size  before  the  sporangium 
falls  off.  As  the  walls  of  the  ovule  harden,  the  carpel  or  leaf 
bearing  it  undergoes  a  similar  change,  becoming  extremely 
hard  and  woody,  and  as  each  one  ends  in  a  sharp  spine,  and 
they  are  tightly  packed  together,  it  is  almost  impossible  to 
separate  them.  The  ripe  cone  (Fig.  75,  A)  remains  closed 
during  the  winter,  but  in  the  spring,  about  the  time  the  flowers 
are  mature,  the  scales  open  spontaneously  and  discharge  the 
ripened  ovules,  now  called  seeds.  Each  seed  (E,  s)  is  sur- 
rounded by  a  membranous  envelope  derived  from  the  scale  to 
which  it  is  attached,  which  becomes  easily  separated  from  the 
seed.  The  opening  of  the  cones  is  caused  by  drying,  and  if 
a  number  of  ripe  cones  are  gathered  in  the  winter  or  early 
spring,  and  allowed  to  dry  in  an  ordinary  room,  they  will  in 


134  BOTANY. 

a  day  or  two  open,  often  with  a  sharp,  crackling  sound,  and 
scatter  the  ripe  seeds. 

A  section  of  a  ripe  seed  (F)  shows  the  embryo  (em.)  sur- 
rounded by  a  dense,  white,  starch-bearing  tissue  derived  from 
the  prothallium  cells,  and  called  the  "  endosperm."  This  fills 
up  the  whole  seed  which  is  surrounded  by  the  hardened  shell 
derived  from  the  integument  and  wall  of  the  ovule.  The 
embryo  is  elongated  with  a  circle  of  small  leaves  at  the  end 
away  from  the  opening  of  the  ovule  toward  which  is  directed 
the  root  of  the  embryo. 

The  seed  may  remain  unchanged  for  months,  or  even  years, 
without  losing  its  vitality,  but  if  the  proper  conditions  are 
provided,  the  embryo  will  develop  into  a  new  plant.  To  follow 
the  further  growth  of  the  embryo,  the  ripe  seeds  should  be 
planted  in  good  soil  and  kept  moderately  warm  and  moist. 
At  the  end  of  a  week  or  two  some  of  the  seeds  will  probably 
have  sprouted.  The  seed  absorbs  water,  and  the  protoplasm 
of  the  embryo  renews  its  activity,  beginning  to  feed  upon  the 
nourishing  substances  in  the  cells  of  the  endosperm.  The 
embryo  rapidly  increases  in  length,  and  the  root  pushes  out 
of  the  seed  growing  rapidly  downward  and  fastening  itself  in 
the  soil  (G,  r).  Cutting  the  seed  lengthwise  we  find  that  the 
leaves  have  increased  much  in  length  and  become  green  (one 
of  the  few  cases  where  chlorophyll  is  formed  in  the  absence 
of  light).  As  these  leaves  (called  "cotyledons"  or  seed  leaves) 
increase  in  length,  they  gradually  withdraw  from  the  seed 
whose  contents  they  have  exhausted,  and  the  young  plant 
enters  upon  an  independent  existence. 

The  young  plant  has  a  circle  of  leaves,  about  six  in  number, 
surrounding  a  bud  which  is  the  growing  point  of  the  stem,  and 
in  many  conifers  persists  as  long  as  the  stem  grows  (Fig.  75, 
K,  b).  A  cross-section  of  the  young  stem  shows  about  six 
separate  fibro-vascular  bundles  arranged  in  a  circle  (8,  fb.). 
The  root  shows  a  central  fibro-vascular  cylinder  surrounded  by 


SPEEMAPHTTES :  PH^ENOGAMS.  135 

a  dark-colored  ground  tissue.     Growing  from  its  surface  are 
numerous  root  hairs  (Fig.  75,  M ) . 

For  examining  the  microscopic  structure  of  the  pine,  fresh  material  is 
for  most  purposes  to  be  preferred,  but  alcoholic  material  will  answer,  and 
as  the  alcohol  hardens  the  resin,  it  is  for  that  reason  preferable. 

Cross- sections  of  the  leaf,  when  sufficiently  magnified,  show  that  the 
outer  colorless  border  of  the  section  is  composed  of  two  parts :  the  epi- 
dermis of  a  single  row  of  regular  cells  with  very  thick  outer  walls,  and 
irregular  groups  of  cells  lying  below  them.  These  latter  have  thick  walls 
appearing  silvery  and  clearer  than  the  epidermal  cells.  They  vary  a  good 
deal,  in  some  leaves  being  reduced  to  a  single  row,  in  others  forming  very 
conspicuous  groups  of  some  size.  The  green  tissue  of  the  leaf  is  much 
more  compact  than  in  the  fern  we  examined,  and  the  cells  are  more  nearly 
round  and  the  intercellular  spaces  smaller.  The  chloroplasts  are  numer- 
ous and  nearly  round  in  shape. 

Scattered  through  the  green  tissue  are  several  resin  passages  (r),  each 
surrounded  by  a  circle  of  colorless,  thick-walled  cells,  like  those  under  the 
epidermis.  At  intervals  in  the  latter  are  openings  —  breathing  pores  — 
(Fig.  76,  «/),  below  each  of  which  is  an  intercellular  space  (i).  They  are 
in  structure  like  those  of  the  ferns,  but  the  walls  of  the  guard  cells  are 
much  thickened  like  the  other  epidermal  cells. 

Each  leaf  is  traversed  by  two  fibro-vascular  bundles  of  entirely  dif- 
ferent structure  from  those  of  the  ferns.  Each  is  divided  into  two  nearly 
equal  parts,  the  wood  (x)  lying  toward  the  inner,  flat  side  of  the  leaf,  the 
bast  (T)  toward  the  outer,  convex  side.  This  type  of  bundle,  called 
"collateral,"  is  the  common  form  found  in  the  stems  and  leaves  of  seed 
plants.  The  cells  of  the  wood  or  xylem  are  rather  larger  than  those  of 
the  bast  or  phloem,  and  have  thicker  walls  than  any  of  the  phloem  cells, 
except  the  outermost  ones  which  are  thick- walled  fibres  like  those  under 
the  epidermis.  Lying  between  the  bundles  are  comparatively  large  color- 
less cells,  and  surrounding  the  whole  central  area  is  a  single  line  of  cells 
that  separates  it  sharply  from  the  surrounding  green  tissue. 

In  longitudinal  sections,  the  cells,  except  of  the  mesophyll  (green  tissue) 
are  much  elongated.  The  mesophyll  cells,  however,  are  short  and  the 
intercellular  spaces  much  more  evident  than  in  the  cross-section.  The 
colorless  cells  have  frequently  rounded  depressions  or  pits  upon  their 
walls,  and  in  the  fibro-vascular  bundle  the  difference  between  the  two 
portions  becomes  more  obvious.  The  wood  is  distinguished  by  the  presence 
of  vessels  with  close,  spiral  or  ring-shaped  thickenings,  while  in  the  phloem 
are  found  sieve  tubes,  not  unlike  those  in  the  ferns. 


136 


BOTANY. 


The  fibro-vascular  bundles  of  the  stem  of  the  seedling  plant  show  a 
structure  quite  similar  to  that  of  the  leaf,  but  very  soon  a  difference  is 
manifested.  Between  the  two  parts  of  the  bundle  the  cells  continue  to 
divide  and  add  constantly  to  the  size  of  the  bundle,  and  at  the  same  time 


cam. 


two-year-old  branch  at  the  point  where  the  two  growth  rings  join :  i,  the 
cells  of  the  first  year's  growth ;  n,  those  of  the  second  year,  m,  a  medullary 
ray,  x  150.  D,  longitudinal  section  of  a  branch,  showing  the  form  of  the 
tracheids  and  the  bordered  pits  upon  their  walls,  m,  medullary  ray,  x  150. 
E,  part  of  a  sieve  tube,  x  300.  F,  cross-section  of  a  tracheid  passing  through 
two  of  the  pits  in  the  wall  (p),  x  300.  G,  longitudinal  section  of  a  branch, 
at  right  angles  to  the  medullary  rays  (m).  At  y,  the  section  has  passed 
through  the  wall  of  a  tracheid,  bearing  a  row  of  pits,  x  150.  H,  cross-section 
of  a  resin  duct,  x  150.  /,  cross-section  of  a  leaf,  x  20.  fb.  nbro-yascular 
bundle,  r,  resin  duct.  J,  section  of  a  breathing  pore,  x  150.  i,  the  air  space 
below  it. 

the  bundles  become  connected  by  a  line  of  similar  growing  cells,  so  that 
very  early  we  find  a  ring  of  growing  cells  extending  completely  around 
the  stem.  As  the  cells  in  this  ring  increase  in  number,  owing  to  their 
rapid  division,  those  on  the  borders  of  the  ring  lose  the  power  of  dividing, 


SPERMAPH YTES :  PH^NOGAMS.  137 

and  gradually  assume  the  character  of  the  cells  on  which  they  border 
(Fig.  76,  B,  cam.}.  The  growth  on  the  inside  of  the  ring  is  more  rapid 
than  on  the  outer  border,  and  the  ring  continues  comparatively  near  the 
surface  of  the  stem  (Fig.  76,  A,  cam.}.  The  spaces  between  the  bundles 
do  not  increase  materially  in  breadth,  and  as  the  bundles  increase  in  size 
become  in  comparison  very  small,  appearing  in  older  stems  as  mere  lines 
between  the  solid  masses  of  wood  that  make  up  the  inner  portion  of  the 
bundles.  These  are  the  primary  medullary  rays,  and  connect  the  pith 
in  the  centre  of  the  stem  with  the  bark.  Later,  similar  plates  of  cells  are 
formed,  often  only  a  single  cell  thick,  and  appearing  when  seen  in  cross- 
section  as  a  single  row  of  elongated  cells  (O,  TO). 

As  the  stem  increases  in  diameter  the  bundles  become  broader  and 
broader  toward  the  outside,  and  taper  to  a  point  toward  the  centre,  appear- 
ing wedge-shaped,  the  inner  ends  projecting  into  the  pith.  The  outer  limits 
of  the  bundles  are  not  nearly  so  distinct,  and  it  is  not  easy  to  tell  when 
the  phloem  of  the  bundles  ends  and  the  ground  tissue  of  the  bark  begins. 

A  careful  examination  of  a  cross-section  of  the  bark  shows  first,  if 
taken  from  a  branch  not  more  than  two  or  three  years  old,  the  epidermis 
composed  of  cells  not  unlike  those  of  the  leaf,  but  whose  walls  are  usually 
browner.  Underneath  are  cells  with  brownish  walls,  and  often  more  or 
less  dry  and  dead.  These  cells  give  the  brown  color  to  the  bark,  and 
later  both  epidermis  and  outer  ground  tissue  become  entirely  dead  and 
disappear.  The  bulk  of  the  ground  tissue  is  made  up  of  rather  large, 
loose  cells,  the  outer  ones  containing  a  good  deal  of  chlorophyll.  Here 
and  there  are  large  resin  ducts  (Fig.  76,  H],  appearing  in  cross-section  as 
oval  openings  surrounded  by  several  concentric  rows  of  cells,  the  inner- 
most smaller  and  with  denser  contents.  These  secrete  the  resin  that 
fills  the  duct  and  oozes  out  when  the  stem  is  cut.  All  of  the  cells  of  the 
bark  contain  more  or  less  starch. 

The  phloem,  when  strongly  magnified,  is  seen  to  be  made  up  of  cells 
arranged  in  nearly  regular  radiating  rows.  Their  walls  are  not  very  thick 
and  the  cells  are  usually  somewhat  flattened  in  a  radial  direction. 

Some  of  the  cells  are  larger  than  the  others,  and  these  are  found  to  be, 
when  examined  in  longitudinal  section,  sieve  tubes  (Fig.  76,  E)  with 
numerous  lateral  sieve  plates  quite  similar  to  those  found  in  the  stems 
of  ferns. 

The  growing  tissue  (cambium),  separating  the  phloem  from  the  wood, 
is  made  up  of  cells  quite  like  those  of  the  phloem,  into  which  they  insen- 
sibly merge,  except  that  their  walls  are  much  thinner,  as  is  always  the 
case  with  rapidly  growing  cells.  These  cells  ( Z?,  cam. )  are  arranged  in 
radial  rows  and  divide,  mainly  by  walls,  at  right  angles  to  the  radii  of 


138  BOTANY. 

the  stein.  If  we  examine  the  inner  side  of  the  ring,  the  change  the  cells 
undergo  is  more  marked.  They  become  of  nearly  equal  diameter  in  all 
directions,  and  the  walls  become  woody,  showing  at  the  same  time  distinct 
stratification  (J5,  x). 

On  examining  the  xylem,  where  two  growth  rings  are  in  contact,  the 
reason  of  the  sharply  marked  line  seen  when  the  stem  is  examined  with 
the  naked  eye  is  obvious.  On  the  inner  side  of  this  line  (/),  the  wood 
cells  are  comparatively  small  and  much  flattened,  while  the  walls  are 
quite  as  heavy  as  those  of  the  much  larger  cells  (//)  lying  on  the  outer 
side  of  the  line.  The  small  cells  show  the  point  where  growth  ceased  at 
the  end  of  the  season,  the  cells  becoming  smaller  as  growth  was  feebler. 
The  following  year  when  growth  commenced  again,  the  first  wood  cells 
formed  by  the  cambium  were  much  larger,  as  growth  is  most  vigorous  at 
this  time,  and  the  wood  formed  of  these  larger  cells  is  softer  and  lighter 
colored  than  that  formed  of  the  smaller  cells  of  the  autumn  growth. 

The  wood  is  mainly  composed  of  tracheids,  there  being  no  vessels 
formed  except  the  first  year.  These  tracheids  are  characterized  by  the 
presence  of  peculiar  pits  upon  their  walls,  best  seen  when  thin  longi- 
tudinal sections  are  made  in  a  radial  direction.  These  pits  (Fig.  70, 
Z>,  p)  appear  in  this  view  as  double  circles,  but  if  cut  across,  as  often 
happens  in  a  cross-section  of  the  stem,  or  in  a  longitudinal  section  at 
right  angles  to  the  radius  (tangential),  they  are  seen  to  be  in  shape  some- 
thing like  an  inverted  saucer  with  a  hole  through  the  bottom.  They  are 
formed  in  pairs,  one  on  each  side  of  the  wall  of  adjacent  tracheids,  and 
are  separated  by  a  very  delicate  membrane  (F,  p,  6r,  y).  These  "bor- 
dered" pits  are  very  characteristic  of  the  wood  of  all  conifers. 

The  structure  of  the  root  is  best  studied  in  the  seedling  plant,  or  in  a 
rootlet  of  an  older  one.  The  general  plan  of  the  root  is  much  like  that 
of  the  pteridophytes.  The  fibro-vascular  bundle  (Fig.  75,  If,  /6.)  is  of 
the  so-called  radial  type,  there  being  three  xylem  masses  (x)  alternating 
with  as  many  phloem  masses  (ph)  in  the  root  of  the  seedling.  This 
regularity  becomes  destroyed  as  the  root  grows  older  by  the  formation  of 
a  cambium  ring,  something  like  that  in  the  stem. 

The  development  of  the  sporangia  is  on  the  whole  much  like  that  of 
the  club  mosses,  and  will  not  be  examined  here  in  detail.  The  microspores 
(pollen  spores)  are  formed  in  groups  of  four  in  precisely  the  same  way  as 
the  spores  of  the  bryophytes  and  pteridophytes,  and  by  collecting  the  male 
flowers  as  they  begin  to  appear  in  the  spring,  and  crushing  the  sporangia 
in  water,  the  process  of  division  may  be  seen.  For  more  careful  exami- 
nation they  may  be  crushed  in  a  mixture  of  water  and  acetic  acid,  to 
which  is  added  a  little  gentian  violet.  This  mixture  fixes  and  stains  the 


SPEEMAPHYTES  :  PHJENOGAMS. 


139 


nuclei  of  the   spores,  and  very  instructive  preparations  may  thus  be 
made.1 

The  ripe  pollen  spores  (Fig.  77,  D)  are  oval  cells  provided  with  a  double 
wall,  the  outer  one  giving  rise  to  two  peculiar  bladder-like  appendages  (z). 
Like  the  microspores  of  the  smaller  club  mosses,  a  small  cell  is  cut  off 


ar. 


in. 


FIG.  77.  —  Scotch  pine  (except  E  and  F}.  A,  end  of  a  branch  bearing  a  cluster 
of  male  flowers  (<3),  x  %.  B,  a  similar  branch,  with  two  young  female 
flowers  (?),  natural  size.  C,  a  scale  from  a  male  flower,  showing  the  two 
sporangia  (sp.),  x  5.  D,  a  single  ripe  pollen  spore  (microspore),  showing  the 
vegetative  cell  (x),  x  150.  E,  a  similar  scale,  from  a  female  flower  of  the 
Austrian  pine,  seen  from  within,  x  4.  o,  the  sporangium  (ovule).  F,  the 
same,  seen  from  the  back,  showing  the  scale  (sc.)  attached  to  the  back.  G, 
longitudinal  section  through  a  full-grown  ovule  of  the  Scotch  pine,  p,  a 
pollen  spore  sending  down  its  tube  to  the  archegonia  (ar.).  sp.  the  prothal- 
lium  (endosperm) ,  filling  up  the  embryo  sac,  x  10.  //,  the  neck  of  the  arche- 
gonium,  x  150. 

from  the  body  of  the  spore  (x).     These  pollen  spores  are  carried  by  the 
wind  to  the  ovules,  where  they  germinate. 

The  wall  of  the  ripe  sporangium  or  pollen  sac  is  composed  of  a  single 
layer  of  cells  in  most  places,  and  these  cells  are  provided  with  thickened 
ridges  which  have  to  do  with  opening  the  pollen  sac. 


See  the  last  chapter  for  details. 


140  BOTANY. 

We  have  already  examined  in  some  detail  the  structure  of  the  macro- 
sporangium  or  ovule.  In  the  full-grown  ovule  the  macrospore,  which  in 
the  seed  plants  is  generally  known  as  the  "embryo  sac,"  is  completely 
filled  with  the  prothallium  or  "endosperm."  In  the  upper  part  of  the 
prothallium  several  large  archegonia  are  formed  in  much  the  same  way 
as  in  the  pteridophytes.  The  egg  cell  is  very  large,  and  appears  of  a  yel- 
lowish color,  and  filled  with  large  drops  that  give  it  a  peculiar  aspect. 
There  is  a  large  nucleus,  but  it  is  not  always  readily  distinguished  from 
the  other  contents  of  the  egg  cell.  The  neck  of  the  archegonium  is  quite 
long,  but  does  not  project  above  the  surface  of  the  prothallium  (Fig.  77,  H). 

The  pollen  spores  are  produced  in  great  numbers,  and  many 
of  them  fall  upon  the  female  flowers,  which  when  ready  for 
pollination  have  the  scales  somewhat  separated.  The  pollen 
spores  now  sift  down  to  the  base  of  the  scales,  and  finally 
reach  the  opening  of  the  ovule,  where  they  germinate.  No 
spermatozoids  are  produced,  the  seed  plants  differing  in  this 
respect  from  all  pteridophytes.  The  pollen  spore  bursts  its 
outer  coat,  and  sends  out  a  tube  which  penetrates  for  some 
distance  into  the  tissue  of  the  ovule,  acting  very  much  as  a 
parasitic  fungus  would  do,  and  growing  at  the  expense  of  the 
tissue  through  which  it  grows.  After  a  time  growth  ceases, 
and  is  not  resumed  until  the  development  of  the  female  pro- 
thallium  and  archegonia  is  nearly  complete,  which  does  not 
occur  until  more  than  a  year  from  the  time  the  pollen  spore 
first  reaches  the  ovule.  Finally  the  pollen  tube  penetrates 
down  to  and  through  the  open  neck  of  the  archegonium,  until 
it  comes  in  contact  with  the  egg  cell.  These  stages  can  only 
be  seen  by  careful  sections  through  a  number  of  ripe  ovules, 
but  the  track  of  the  pollen  tube  is  usually  easy  to  follow,  as 
the  cells  along  it  are  often  brown  and  apparently  dead  (Fig. 
77,  G). 

CLASSIFICATION  OF  THE  GYMNOS PERMS. 

There  are  three  classes  of  the  gymnosperms :  I.,  cycads 
(Cycadece)-,  II.,  conifers  (Coniferce),  III.,  joint  firs  (Gnetacece). 
All  of  the  gymnosperms  of  the  northern  United  States  belong 


SPEEMAPH TTES :   PHJZNOGAMS. 


141 


to  the  second  order,  but  representatives  of  the  others  are 
found  in  the  southern  and  southwestern  states. 

The  cycads  are  palm-like  forms  having  a  single  trunk 
crowned  by  a  circle  of  compound  leaves.  Several  species  are 
grown  for  ornament  in  conservatories,  and  a  few  species  occur 
native  in  Florida,  but  otherwise  do  not  occur  within  our  limits. 

The  spore-bearing  leaves  usually  form  cones,  recalling  some- 


FIG.  78.  —  Illustrations  of  gymnosperms.  A,  fruiting  leaf  of  a  cycad  (Cycas), 
with  macrosporangia  (ovules)  (ou.),  x  y4.  B,  leaf  of  Gingko,  x  y2.  C,  branch 
of  hemlock  (Tsuc/a),  with  a  ripe  cone,  x  1.  D,  red  cedar  (Juniperus),  x  1. 
E,  Arbor-vitsB  ( Thuja) ,  x  1. 

what  in  structure  those  of  the  horse-tails,  but  one  of  the  com- 
monest cultivated  species  (Cycas  revoluta)  bears  the  ovules, 
which  are  very  large,  upon  leaves  that  are  in  shape  much  like 
the  ordinary  ones  (Fig.  78,  A). 

Of  the  conifers,  there  are  numerous  familiar  forms,  including 
all  our  common  evergreen  trees.  There  are  two  sub-orders,  — 
the  true  conifers  and  the  yews.  In  the  latter  there  is  no  true 


142  BOTANY. 

cone,  but  the  ovules  are  borne  singly  at  the  end  of  a  branch, 
and  the  seed  in  the  yew  (Taxus)  is  surrounded  by  a  bright 
red,  fleshy  integument.  One  species  of  yew,  a  low,  straggling 
shrub,  occurs  sparingly  in  the  northern  states,  and  is  the  only 
representative  of  the  group  at  the  north.  The  European  yew 
and  the  curious  Japanese  GingJco  (Fig.  78,  JB)  are  sometimes 
met  with  in  cultivation. 

Of  the  true  conifers,  there  are  a  number  of  families,  based 
on  peculiarities  in  the  leaves  and  cones.  Some  have  needle- 
shaped  leaves  and  dry  cones  like  the  firs,  spruces,  hemlock 
(Fig.  78,  C).  Others  have  flattened,  scale-like  leaves,  and 
more  or  less  fleshy  cones,  like  the  red  cedar  (Fig.  78,  D)  and 
Arbor-vitce  (E). 

A  few  of  the  conifers,  such  as  the  tamarack  or  larch  (Larix) 
and  cypress  (Taxodium),  lose  their  leaves  in  the  autumn,  and 
are  not,  therefore,  properly  "evergreen." 

The  conifers  include  some  of  the  most  valuable  as  well  as 
the  largest  of  trees.  Their  timber,  especially  that  of  some  of 
the  pines,  is  particularly  valuable,  and  the  resin  of  some  of 
them  is  also  of  much  commercial  importance.  Here  belong 
the  giant  red-woods  (Sequoia)  of  California,  the  largest  of  all 
American  trees. 

The  joint  firs  are  comparatively  small  plants,  rarely  if  ever 
reaching  the  dimensions  of  trees.  They  are  found  in  various 
parts  of  the  world,  but  are  few  in  number,  and  not  at  all  likely 
to  be  met  with  by  the  ordinary  student.  Their  flowers  are 
rather  more  highly  differentiated  than  those  of  the  other  gym- 
nosperms,  and  are  said  to  show  some  approach  in  structure  to 
those  of  the  angiosperms. 


CHAPTER   XV. 

SPBRMAPHYTBS. 

CLASS  II.  —  ANGIOSPERMS. 

THE  angiosperms  include  an  enormous  assemblage  of  plants, 
all  those  ordinarily  called  "  flowering  plants  "  belonging  here. 
There  is  almost  infinite  variety  shown  in  the  form  and  struc- 
ture of  the  tissues  and  organs,  this  being  particularly  the  case 
with  the  flowers.  As  already  stated,  the  ovules,  instead  of 
being  borne  on  open  carpels,  are  enclosed  in  a  cavity  formed 
by  a  single  closed  carpel  or  several  united  carpels.  To  the 
organ  so  formed  the  name  "pistil "  is  usually  applied,  and  this 
is  known  as  "  simple  "  or  "  compound,"  as  it  is  composed  of 
one  or  of  two  or  more  carpels.  The  leaves  bearing  the  pollen 
spores  are  also  much  modified,  and  form  the  so-called  "sta- 
mens." In  addition  to  the  spore-bearing  leaves  there  are 
usually  other  modified  leaves  surrounding  them,  these  being 
often  brilliantly  colored  and  rendering  the  flower  very  conspic- 
uous. To  these  leaves  surrounding  the  sporophylls,  the  general 
name  of  "perianth"  or  "perigone"  is  given.  The  perigone 
has  a  twofold  purpose,  serving  both  to  protect  the  sporophylls, 
and,  at  least  in  bright-colored  flowers,  to  attract  insects  which, 
as  we  shall  see,  are  important  agents  in.  transferring  pollen 
from  one  flower  to  another. 

When  we  compare  the  embryo  sac  (macrospore)  of  the 
angiosperms  with  that  of  the  gymnosperms  a  great  difference 
is  noticed,  there  being  much  more  difference  than  between  the 
latter  and  the  higher  pteridophytes.  Unfortunately  there  are 
very  few  plants  where  the  structure  of  the  embryo  sac  can  be 
readily  seen  without  very  skilful  manipulation. 

143 


144 


BOTANY. 


There  are,  however,  a  few  plants  in  which  the  ovules  are  very  small 
and  transparent,  so  that  they  may  be  mounted  whole  and  examined  alive. 
The  best  plant  for  this  purpose  is  probably  the  "  Indian  pipe"  or  "ghost 
flower,"  a  curious  plant  growing  in  rich  woods,  blossoming  in  late  summer. 
It  is  a  parasite  or  saprophyte,  and  entirely  destitute  of  chlorophyll,  being 

pure  white  throughout.  It  bears  a 
single  nodding  flower  at  the  summit 
of  the  stem.  (Another  species  much 
like  it,  but  having  several  brownish 
flowers,  is  shown  in  Figure  115,  L.) 

If  this  plant  can  be  had,  the  struct- 
ure of  the  ovule  and  embryo  sac 
may  be  easily  studied,  by  simply 
stripping  away  the  tissue  bearing  the 
numerous  minute  ovules,  and  mount- 
ing a  few  of  them  in  water,  or  water 
to  which  a  little  sugar  has  been 
added. 

The  ovules  are  attached  to  a  stalk, 
and  each  consists  of  about  two 
layers  of  colorless  cells  enclosing  a 
central,  large,  oblong  cell  (Fig.  79, 
A,  JE"),  the  embryo  sac  or  macrospore. 
If  the  ovule  is  from  a  flower  that 
has  been  open  for  some  time,  we 
shall  find  in  the  centre  of  the  embryo 
sac  a  large  nucleus  (k)  (or  possibly 
two  which  afterward  unite  into  one), 
and  at  each  end  three  cells.  Those 
at  the  base  (g)  probably  represent 
the  prothallium,  and  those  at  the 
upper  end  a  very  rudimentary  arche- 
gonium,  here  generally  called  the 
"egg  apparatus." 

Of  the  three  cells  of  the  "egg  ap- 
paratus "  the  lower  (o)  one  is  the  egg 

cell ;  the  others  are  called  "  synergidse."  The  structure  of  the  embryo  sac 
and  ovules  is  quite  constant  among  the  angiosperms,  the  differences  being 
mainly  in  the  shape  of  the  ovules,  and  the  degree  to  which  its  coverings 
or  integuments  are  developed. 

The  pollen  spores  of  many  angiosperms  will  germinate  very  easily  in 


FIG.  79.  —  A,  ripe  ovule  of  Mono- 
tropa  uniflora,  in  optical  section, 
x  100.  m,  micropyle.  e,  embryo 
sac.  B,  the  embryo  sac,  x  300. 
At  the  top  is  the  egg  apparatus, 
consisting  of  the  two  synergidae 
(s),  and  the  egg  cell  (o).  In  the 
centre  is  the  "  endosperm  nucleus  " 
(fc).  At  the  bottom,  the  "anti- 
pedal  cells  "  (g). 


SPEEMAPHYTES. 


145 


a  solution  of  common  sugar  in  water :  about  fifteen  per  cent  of  sugar  is  the 
best.     A  very  good  plant  for  this  purpose  is  the  sweet  pea,  whose  pollen 
germinates  very  rapidly,  especially  in  warm  weather.     The  spores  may  be 
sown  in  a  little  of  the  sugar  solution 
in  any  convenient  vessel,  or  in  a  hang- 
ing drop  suspended  in  a  moist  cham- 
ber,   as    described   for   germinating 
the  spores  of  the  slime  moulds.     The 
tube  begins  to  develop  within  a  few 
minutes  after  the  spores  are  placed 
in  the  solution,  and  within  an  hour 
or  so  will  have  reached  a  considerable 
length.    Each  spore  has  two  nuclei, 
but  they  are  less  evident  here  than  in 
some  other  forms  (Fig.  79). 


FIG.  80.  —  Germinating  pollen  spores 
of  the  sweet  pea,  x  200. 


The  upper  part  of  the  pistil 
is  variously  modified,  having 
either  little  papillae  which  hold 
the  pollen  spores,  or  are  viscid. 

In  either  case  the  spores  germinate  when  placed  upon  this 
receptive  part  (stigma)  of  the  pistil,  and  send  their  tubes 
down  through  the  tissues  of  the  pistil  until  they  reach  the 
ovules,  which  are  fertilized  much  as  in  the  gymnosperms. 

The  effect  of  fertilization  extends  beyond  the  ovule,  the 
ovary  and  often  other  parts  of  the  flower  being  affected,  en- 
larging and  often  becoming  bright-colored  and  juicy,  forming 
the  various  fruits  of  the  angiosperms.  These  fruits  when  ripe 
may  be  either  dry,  as  in  the  case  of  grains  of  various  kinds, 
beans,  peas,  etc. ;  or  the  ripe  fruit  may  be  juicy,  serving  in  this 
way  to  attract  animals  of  many  kinds  which  feed  on  the  juicy 
pulp,  and  leave  the  hard  seeds  uninjured,  thus  helping  to  distrib- 
ute them.  Common  examples  of  these  fleshy  fruits  are  offered 
by  the  berries  of  many  plants ;  apples,  melons,  cherries,  etc., 
are  also  familiar  examples. 

The  seeds  differ  a  good  deal  both  in  regard  to  size  and  the  de- 
gree to  which  the  embryo  is  developed  at  the  time  the  seed  ripens. 


146  BOTANY. 


CLASSIFICATION  OF  THE  ANGIOSPERMS. 

The  angiosperms  are  divided  into  two  sub-classes :  I.  Mono- 
cotyledons and  II.  Dicotyledons. 

The  monocotyledons  comprise  many  familiar  plants,  both 
ornamental  and  useful.  They  have  for  the  most  part  elon- 
gated, smooth-edged  leaves  with  parallel  veins,  and  the  parts 
of  the  flower  are  in  threes  in  the  majority  of  them.  As  their 
name  indicates,  there  is  but  one  cotyledon  or  seed  leaf,  and  the 
leaves  from  the  first  are  alternate.  As  a  rule  the  embryo  is 
very  small  and  surrounded  by  abundant  endosperm. 

The  most  thoroughly  typical  members  of  the  sub-class  are 
the  lilies  and  their  relatives.  The  one  selected  for  special 
study  here,  the  yellow  adder-tongue,  is  very  common  in  the 
spring ;  but  if  not  accessible,  almost  any  liliaceous  plant  will 
answer.  Of  garden  flowers,  the  tulip,  hyacinth,  narcissus,  or 
one  of  the  common  lilies  may  be  used ;  of  wild  flowers,  the 
various  species  of  Trillium  (Fig.  83,  A)  are  common  and  easily 
studied  forms,  but  the  leaves  are  not  of  the  type  common  to 
most  monocotyledons. 

The  yellow  adder-tongue  (Erythronium  americanum)  (Fig. 
81)  is  one  of  the  commonest  and  widespread  of  wild  flowers, 
blossoming  in  the  northern  states  from  about  the  middle  of 
April  till  the  middle  of  May.  Most  of  the  plants  found  will 
not  be  in  flower,  and  these  send  up  but  a  single,  oblong,  pointed 
leaf.  The  flowering  plant  has  two  similar  leaves,  one  of  which 
is  usually  larger  than  the  other.  They  seem  to  come  directly 
from  the  ground,  but  closer  examination  shows  that  they  are 
attached  to  a  stem  of  considerable  length  entirely  buried  in 
the  ground.  This  arises  from  a  small  bulb  (5)  to  whose  base 
numerous  roots  (r)  are  attached.  Rising  from  between  the 
leaves  is  a  slender,  leafless  stalk  bearing  a  single,  nodding 
flower  at  the  top. 

The  leaves  are  perfectly  smooth,  dull  purplish  red  on  the 


SPEBMAPHYTES. 


147 


lower  side,  and  pale  green  with  purplish  blotches  above.  The 
epidermis  may  be  very  easily  removed,  and  is  perfectly  color- 
less. Examined  closely,  longitudinal  rows  of  whitish  spots 
may  be  detected :  these  are  the  breathing  pores. 

A  cross-section  of  the  stem  shows  numerous  whitish  areas 


,-sp. 


FIG.  81.  —  A,  plant  of  the  yellow  adder-tongue  (Erythronium  americanum), 
x  Vs.  B,  the  bulb  of  the  same,  x  %.  r,  roots.  C,  section  of  B.  st.  the  base 
of  the  stem  bearing  the  bulb  for  next  year  (6)  at  its  base.  D,  a  single  petal 
and  stamen,  x  %.  /,  the  filament,  an.  anther.  E,  the  gynoecium  (pistil), 
x  1.  o,  ovary,  st.  style,  z,  stigma.  F,  a  full-grown  fruit,  x  %.  G,  section 
of  a  full-grown  macrosporangium  (ovule),  x  25  :  i,  n,  the  two  integuments. 
sp.  macrospore  (embryo  sac).  //,  cross-section  of  the  ripe  anther,  x  12.  /,  a 
single  pollen  spore,  x  150,  showing  the  two  nuclei  (n,  n').  J,  a  ripe  seed, 
x  2.  K,  the  same,  in  longitudinal  section,  em.  the  embryo.  L,  cross-section 
of  the  stem,  x  12.  fb.  fibro-vascular  bundle.  M,  diagram  of  the  flower. 

scattered  through  it.  These  are  the  fibro-vascular  bundles 
which  in  the  monocotyledons  are  of  a  simple  type.  The  bulb 
is  composed  of  thick  scales,  which  are  modified  leaves,  and  on 
cutting  it  lengthwise,  we  shall  probably  find  the  young  bulb 
of  next  year  (Fig.  C,  b)  already  forming  inside  it,  the  young 


148  BOTANY. 

bulb  arising  as  a  bud  at  the  base  of  the  stem  of  the  present 
year. 

The  flower  is  made  up  of  five  circles  of  very  much  modified 
leaves,  three  leaves  in  each  set.  The  two  outer  circles  are 
much  alike,  but  the  three  outermost  leaves  are  slightly  nar- 
rower and  strongly  tinged  with  red  on  the  back,  completely 
concealing  the  three  inner  ones  before  the  flower  expands. 
The  latter  are  pure  yellow,  except  for  a  ridge  along  the  back, 
and  a  few  red  specks  near  the  base  inside.  These  six  leaves 
constitute  the  perigone  of  the  flower ;  the  three  outer  are  called 
sepals,  the  inner  ones  petals. 

The  next  two  circles  are  composed  of  the  sporophylls  bear- 
ing the  pollen  spores.1  These  are  the  stamens,  and  taken 
collectively  are  known  as  the  " Andrcecium"  Each  leaf  or 
stamen  consists  of  two  distinct  portions,  a  delicate  stalk  or 
"filament'7  (Z>,  /),  and  the  upper  spore-bearing  part,  the 
"anther"  (an.).  The  anther  in  the  freshly  opened  flower  has 
a  smooth,  red  surface ;  but  shortly  after,  the  flower  opens,  splits 
along  each  side,  and  discharges  the  pollen  spores.  A  section 
across  the  anther  shows  it  to  be  composed  of  four  sporangia 
or  pollen  sacs  attached  to  a  common  central  axis  ("connec- 
tive") (Mg.  IT). 

The  central  circle  of  leaves,  the  carpels  (collectively  the 
"gyncecium")  are  completely  united  to  form  a  compound 
pistil  (Fig.  81,  E).  This  shows  three  distinct  portions,  the 
ovule-bearing  portion  below  (o),the  "  ovary,"  a  stalk  above  (st.), 
the  "style,"  and  the  receptive  portion  (z)  at  the  top,  the 
"  stigma."  Both  stigma  and  ovary  show  plainly  their  compound 
nature,  the  former  being  divided  into  three  lobes,  the  latter 
completely  divided  into  three  chambers,  as  well  as  being  flat- 
tened at  the  sides  with  a  more  or  less  decided  seam  at  the 
three  angles.  The  ovules,  which  are  quite  large,  are  arranged 
in  two  rows  in  each  chamber  of  the  ovary,  attached  to  the 
central  column  ("placenta"). 

1  The  three  outer  stamens  are  shorter  than  the  inner  set. 


SPEEMAPH  YTES. 


149 


The  flowers  open  for  several  days  in  succession,  but  only 
when  the  sun  is  shining.  They  are  visited  by  numerous 
insects  which  carry  the  pollen  from  one  flower  to  another  and 
deposit  it  upon  the  stigma,  where  it  germinates,  and  the  tube, 
growing  down  through  the  long  style,  finally  reaches  the 
ovules  and  fertilizes  them.  Usually  only  a  comparatively 


FIG.  82.  —  Erythronium.  A,  a  portion  of  the  wall  of  the  anther,  x  150.  B,  a 
single  epidermal  cell  from  the  petal,  x  150.  C,  cross-section  of  a  fibro- 
vascular  bundle  of  the  stem,  x  150.  tr.  vessels.  I),  E,  longitudinal  section 
of  the  same,  showing  the  markings  of  the  vessels,  x  150.  F,  a  bit  of  the 
epidermis  from  the  lower  surface  of  a  leaf ,  showing  the  breathing  pores,  x  50. 
G,  a  single  breathing  pore,  x  200.  H,  cross-section  of  a  leaf,  x  50.  st.  a 
breathing  pore,  m,  the  mesophyll.  /&.  a  vein.  /,  cross-section  of  a  breath- 
ing pore,  x  200.  J,  young  embryo,  x  150. 

small  number  of  the  seeds  mature,  there  being  almost  always 
a  number  of  imperfect  ones  in  each  pod.  The  pod  or  fruit  (F) 
is  full-grown  about  a  month  after  the  flower  opens,  and  finally 
separates  into  three  parts,  and  discharges  the  seeds.  These  are 
quite  large  (Fig.  81,  J)  and  covered  with  a  yellowish  brown 


150  BOTANY. 

outer  coat,  and  provided  with  a  peculiar,  whitish,  spongy  appen- 
dage attaching  it  to  the  placenta.  A  longitudinal  section  of  a 
ripe  seed  (K)  shows  the  very  small,  nearly  triangular  embryo 
(em.),  while  the  rest  of  the  cavity  of  the  seed  is  filled  with  a 
white,  starch-bearing  tissue,  the  endosperm. 

A  microscopical  examination  of  the  tissues  of  the  plant  shows  them  to 
be  comparatively  simple,  this  being  especially  the  case  with  the  fibro- 
vascular  system. 

The  epidermis  of  the  leaf  is  readily  removed,  and  examination  shows 
it  to  be  made  up  of  oblong  cells  with  large  breathing  pores  in  rows.  The 
breathing  pores  are  much  larger  than  any  we  have  yet  seen,  and  are  of 
the  type  common  to  most  angiosperms.  The  ordinary  epidermal  cells  are 
quite  destitute  of  chlorophyll,  but  the  two  cells  (guard  cells)  enclosing  the 
breathing  pore  contain  numerous  chloroplasts,  and  the  oblong  nuclei  of 
these  cells  are  usually  conspicuous  (Fig.  82,  G).  By  placing  a  piece  of  the 
leaf  between  pieces  of  pith,  and  making  a  number  of  thin  cross- sections 
at  right  angles  to  the  longer  axis  of  the  leaf,  some  of  the  breathing  pores 
will  probably  be  cut  across,  and  their  structure  may  be  'then  better  under- 
stood. Such  a  section  is  shown  in  Figure  82,  /. 

The  body  of  the  leaf  is  made  up  of  chlorophyll- bearing  cells  of  irregular 
shape  and  with  large  air  spaces  between  (77,  in).  The  veins  traversing 
this  tissue  are  fibro- vascular  bundles  of  a  type  structure  similar  to  that  of 
the  stem,  which  will  be  described  presently. 

The  stem  is  made  up  principally  of  large  cells  with  thin  walls,  which  in 
cross-section  show  numerous  small,  triangular,  intercellular  spaces  (i)  at 
the  angles.  These  cells  contain,  usually,  more  or  less  starch.  The  fibro- 
vascular  bundles  (C)  are  nearly  triangular  in  section,  and  resemble  con- 
siderably those  of  the  field  horse-tail,  but  they  are  not  penetrated  by  the 
air  channel,  found  in  the  latter.  The  xylem,  as  in  the  pine,  is  toward 
the  outside  of  the  stem,  but  the  boundary  between  xylem  and  phloem  is 
not  well  defined,  there  being  no  cambium  present.  In  the  xylem  are  a 
number  of  vessels  (<7,  tr.)  at  once  distinguishable  from  the  other  cells  by 
their  definite  form,  firm  walls^,  and  empty  cavity.  The  vessels  in  longi- 
tudinal sections  show  spiral  and  ringed  thickenings.  The  rest  of  the 
xylem  cells,  as  well  as  those  of  the  phloem,  are  not  noticeably  different 
from  the  cells  of  the  ground  tissue,  except  for  their  much  smaller  size, 
and  absence  of  intercellular  spaces. 

The  structure  of  the  leaves  of  the  perigone  is  much  like  that  of  the 
green  leaves,  but  the  tissues  are  somewhat  reduced.  The  epidermis  of 


SPERM  A  PHYTES.  151 

the  outer  side  of  the  sepals  has  breathing  pores,  but  these  are  absent  from 
their  inner  surface,  and  from  both  sides  of  the  petals.  The  walls  of  the 
epidermal  cells  of  the  petals  are  peculiarly  thickened  by  apparent  infold- 
ings  of  the  wall  (5),  and  these  cells,  as  well  as  those  below  them,  contain 
small,  yellow  bodies  (chromoplasts)  to  which  the  bright  color  of  the  flower 
is  due.  The  red  specks  on  the  base  of  the  perigone  leaves,  as  well  as  the 
red  color  of  the  back  of  the  sepals,  the  stalk,  and  leaves  are  due  to  a  pur- 
plish red  cell  sap  filling  the  cells  at  these  points. 

The  filaments  or  stalks  of  the  stamens  are  made  up  of  very  delicate  col- 
orless cells,  and  the  centre  is  traversed  by  a  single  fibro-vascular  bundle, 
which  is  continued  up  through  the  centre  of  the  anther.  To  study  the 
latter,  thin  cross-sections  should  be  made  and  mounted  in  water.  Each 
of  the  four  sporangia,  or  pollen  sacs,  is  surrounded  on  the  outside  by  a 
wall,  consisting  of  two  layers  of  cells,  becoming  thicker  in  the  middle  of 
the  section  where  the  single  fibro-vascular  bundle  is  seen  (Fig.  81,  H).  On 
opening,  the  cavities  of  the  adjacent  sporangia  are  thrown  together.  The 
inner  cells  of  the  wall  are  marked  by  thickened  bars,  much  as  we  saw  in 
the  pine  (Fig.  82,  A),  and  which,  like  these,  are  formed  shortly  before  the 
pollen  sacs  open.  The  pollen  spores  (Fig.  81,  /)  are  large,  oval  cells,  having 
a  double  wall,  the  outer  one  somewhat  heavier  than  the  inner  one,  but  suffi- 
ciently transparent  to  allow  a  clear  view  of  the  interior,  which  is  filled  with 
very  dense,  granular  protoplasm  in  which  may  be  dimly  seen  two  nuclei 
(n,  ni.),  showing  that  here  also  there  is  a  division  of  the  spore  contents, 
although  no  wall  is  present.  The  spores  do  not  germinate  very  readily, 
and  are  less  favorable  for  this  purpose  than  those  of  some  other  mono- 
cotyledons. Among  the  best  for  this  purpose  are  the  spiderwort  ( Trades- 
cantia)  and  Scilla. 

Owing  to  the  large  size  and  consequent  opacity  of  the  ovules,  as  well 
as  to  the  difficulty  of  getting  the  early  stages,  the  development  and  finer 
structure  of  the  ovule  will  not  be  discussed  here.  The  full-grown  ovule 
may  be  readily  sectioned,  and  a  general  idea  of  its  structure  obtained.  A 
little  potash  may  be  used  to  advantage  in  this  study,  carefully  washing  it 
away  when  the  section  is  sufficiently  cleared.  We  find  now  that  the  ovule 
is  attached  to  a  stalk  (funiculus)  (Fig.  81,  £,  /),  the  body  of  the  ovule 
being  bent  up  so  as  to  lie  against  the  stalk.  Such  an  inverted  ovule  is 
called  technically,  "  anatropous. "  The  ovule  is  much  enlarged  where 
the  stalk  bends.  The  upper  part  of  the  ovule  is  on  the  whole  like  that  of 
the  pine,  but  there  are  two  integuments  (i,  n)  instead  of  the  single  one 
found  in  the  pine. 

As  the  seed  develops,  the  embryo  sac  (6r,  sp.)  enlarges  so  as  to  occupy 
pretty  much  the  whole  space  of  the  seed.  At  first  it  is  nearly  filled  with 


152  BOTANY. 

a  fluid,  but  a  layer  of  cells  is  formed,  lining  the  walls,  and  this  thickens 
until  the  whole  space,  except  what  is  occupied  by  the  small  embryo,  is 
filled  with  them.  These  are  called  the  "endosperm  cells,"  but  differ 
from  the  endosperm  cells  of  the  gymnosperms,  in  the  fact  that  they  are 
not  developed  until  after  fertilization,  and  can  hardly,  therefore,  be 
regarded  as  representing  the  prothallium  of  the  gymnosperms  and  pteri- 
dophytes.  These  cells  finally  form  a  firm  tissue,  whose  cells  are  filled  with 
starch  that  forms  a  reserve  supply  of  food  for  the  embryo  plant  when  the 
seed  germinates.  The  embryo  (Fig.  81,  7f,  era.,  Fig.  82,  </),  even  when 
the  seed  is  ripe,  remains  very  small,  and  shows  scarcely  any  differentia- 
tion. It  is  a  small,  pear-shaped  mass  of  cells,  the  smaller  end  directed 
toward  the  upper  end  of  the  embryo  sac. 

The  integuments  grow  with  the  embryo  sac,  and  become 
brown  and  hard,  forming  the  shell  of  the  seed.  The  stalk  of 
the  ovule  also  enlarges,  and  finally  forms  the  peculiar,  spongy 
appendage  of  the  seeds  already  noticed  (Fig.  81,  J,  K). 


CHAPTER  XVI. 

CLASSIFICATION  OF  THE  MONOCOTYLEDONS. 

IN  the  following  chapter  no  attempt  will  be  made  to  give  an 
exhaustive  account  of  the  characteristics  of  each  division  of 
the  monocotyledons,  but  only  such  of  the  most  important  ones 
as  may  serve  to  supplement  our  study  of  the  special  one  already 
examined.  The  classification  here,  and  this  is  the  case  through- 
out the  spermaphytes,  is  based  mainly  upon  the  characters  of 
the  flowers  and  fruits. 

The  classification  adopted  here  is  that  of  the  German  botan- 
ist Eichler,  and  seems  to  the  author  to  accord  better  with  our 
present  knowledge  of  the  relationships  of  the  groups  than  do 
the  systems  that  are  more  general  in  this  country.  Accord- 
ing to  Eichler's  classification,  the  monocotyledons  may  be 
divided  into  seven  groups;  viz.,  I.  Liliifloroe,;  II.  Enantio- 
blastce;  III.  Spadiciftorce ;  IV.  Glumacece  ;  V.  Scitaminece;  VI. 
Gynandrce;  VII.  Helobice. 

OKDER  I.  —  Liliifloroe,. 

The  plants  of  this  group  agree  in  their  general  structure 
with  the  adder' s-tongue,  which  is  a  thoroughly  typical  repre- 
sentative of  the  group ;  but  nevertheless,  there  is  much  varia- 
tion among  them  in  the  details  of  structure.  While  most  of 
them  are  herbaceous  forms  (dying  down  to  the  ground  each 
year),  a  few,  among  which  may  be  mentioned  the  yuccas 
("bear  grass,"  "Spanish  bayonet")  of  our  southern  states, 
develop  a  creeping  or  upright  woody  stem,  increasing  in  size 
from  year  to  year.  The  herbaceous  forms  send  up  their  stems 

153 


154 


BOTANY. 


yearly  from  underground  bulbs,  tubers,  e.g.  Trillium  (Fig.  83, 
A),  or  thickened,  creeping  stems,  or  root  stocks  (rhizomes). 
Good  examples  of  the  last  are  the  Solomon's-seal  (Fig.  83,  B), 
Medeola  (C,  D),  and  iris  (Fig.  84  A).  One  family,  the  yams 
(Dioscorece) ,  of  which  we  have  one  common  native  species,  the 
wild  yam  (Dioscorea  villosa),  have  broad,  netted-veined  leaves 
and  are  twining  plants,  while  another  somewhat  similar  family 


FIG.  83.  — Types  of  Liliiflorse.  A,  Trillium,  x  V4.  B,  single  flower  of  Solomon's- 
seal  (Polygonatum),  x  1.  C,  upper  part  of  a  plant.  D,  underground  stem 
(rhizome)  of  Indian  cucumber  root  (Medeola),  x  %.  E,  a  rush  (Juncus),  x  1. 
F,  a  single  flower,  x  2.  A-D,  Liliacese  ;  E,  Jtincacese. 

(Smilacece)  climb  by  means  of  tendrils  at  the  bases  of  the 
leaves.  Of  the  latter  the  "  cat-brier  "  or  "  green-brier  "  is  a 
familiar  representative.' 

The  flowers  are  for  the  most  part  conspicuous,  and  in  plan 
like  that  of  the  adder's-tongue  ;  but  some,  like  the  rushes  (Fig. 
83,  E),  have  small,  inconspicuous  flowers ;  and  others,  like  the 
yams  and  smilaxes,  have  flowers  of  two  kinds,  male  and  female. 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      155 

The  principal  family  of  the  Liliijlorceis  the  Liliacece,  includ- 
ing some  of  the  most  beautiful  of  all  flowers.  All  of  the  true 
lilies  (Lilium),  as  well  as  the  day  lilies  (Funkia,  Hemerocallis) 
of  the  gardens,  tulips,  hyacinths,  lily-of-the-valley,  etc.,  belong 
here,  as  well  as  a  number  of  showy  wild  flowers  including  sev- 


FIG.  84.  —  Types  of  Liliiflorse.  A,  flower  of  the  common  blue-flag  (Iris),  x  % 
(Iridacese).  B,  the  petal-like  upper  part  of  the  pistil,  seen  from  below,  and 
showing  a  stamen  (an.),  st.  the  stigma,  x  %.  C,  the  young  fruit,  x  %.  D, 
section  of  the  same,  x  i.  E,  diagram  of  the  flower.  F,  part  of  a  plant  of  the 
so-called  "  gray  moss "  (Tillandsia) ,  x  y2  (Bromcliacese).  G,  a  single  flower, 
x  2.  H,  a  seed,  showing  the  fine  hairs  attached  to  it,  x  l.  /,  plant  of 
pickerel- weed  (Pontederia),  x  i/4  (Poniederiacese) .  J,  a  single  flower,  x  1. 
K,  section  of  the  ovary,  x  4. 

eral  species  of  tiger-lilies  (Lilium),  various  species  of  Tril- 
lium (Fig.  83,  A),  Solomon's-seal  (Polygonatum)  (Fig.  83,  B), 
bellwort  (Uvularia),  and  others.  In  all  of  these,  except  Trillium) 
the  perigone  leaves  are  colored  alike,  and  the  leaves  parallel- 
veined;  but  in  the  latter  the  sepals  are  green  and  the  leaves 
broad  and  netted-veined.  The  fruit  of  the  Liliacece  may  be 


156 


BOTANY. 


either  a  pod,  like  that  of  the  adder's-tongue,  or  a  berry,  like 
that  of  asparagus  or  Solomon' s-seal. 

Differing  from  the  true  lilies  in  having  the  bases  of  the  peri- 
gone  leaves  adherent  to  the  surface  of  the  ovary,  so  that  the 
latter  is  apparently  below  the  flower  (inferior),  and  lacking 
the  inner  circle  of  stamens,  is  the  iris  family  (/n'daceee),  repre- 
sented by  the  wild  blue-flag  (Iris  versicolor)  (Fig.  84,  A,  JE), 
as  well  as  by  numerous  cultivated  species.  In  iris  the  carpels 
are  free  above  and  colored  like  the  petals  (B),  with  the  stigma 
on  the  under  side.  Of  garden  flowers  the  gladiolus  and  crocus 
are  the  most  familiar  examples,  besides  the  various  species  of 
iris;  and  of  wild  flowers  the  little  "blue-eyed  grass"  (Sisy- 
rinchium) . 

The  blue  pickerel- weed 
(Pontederia)  is  the  type  of  a 
family  of  which  there  are  few 
common  representatives  (Fig. 
84,  I,  A')- 

The  last  family  of  the  order 
is  the  BromeliacecK,  all  inhabi- 
tants of  the  warmer  parts  of  the 
globe,  but  represented  in  the 
southern  states  by  several 
forms,  the  commonest  of  which 
is  the  so-called  "gray  moss  " 
( Tillandsea )  (Fig.  84,  F,  H) .  Of 
cultivated  plants  the  pineapple, 
whose  fruit  consists  of  a  fleshy 
mass  made  up  of  the  crowded  fruits  and  the  fleshy  flower 
stalks,  is  the  best  known. 


FIG.  85.  —  Enantioblastse.  A ,  inflo- 
rescence of  thecommon  spiderwort 
(Tradescantia) ,  x  y2  (Comme- 
lyneee).  B,  a  single  stamen,  show- 
ing the  hairs  attached  to  the  fila- 
ment, x  2.  C,  the  pistil,  x  2. 


ORDER  II.  —  Enantioblastce. 

The    second   order  of   the    monocotyledons,    Enantioblastaz, 
includes  very  few  common  plants.     The  most  familiar  exam- 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      157 

pies  are  the  various  species  of  Tradescantia  (Fig.  88),  some 
of  which  are  native,  others  exotic.  Of  the  cultivated  forms 
the  commonest  is  one  sometimes  called  "  wander  ing- jew,"  a 
trailing  plant  with  zigzag  stems,  and  oval,  pointed  leaves 
forming  a  sheath  about  each  joint.  Another  common  one  is 
the  spiderwort  already  referred  to.  In  this  the  leaves  are  long 
and  pointed,  but  also  sheathing  at  the  base.  When  the  flowers 
are  showy,  as  in  these,  the  sepals  and  petals  are  different,  the 
former  being  green.  The  flowers  usually  open  but  once,  and 
the  petals  shrivel  up  as  the  flower  fades.  There  are  four 
families  of  the  order,  the  spiderwort  belonging  to  the  highest 
one,  Commelynece. 

ORDER  III.  —  Spadicijiorce. 

The  third  order  of  the  monocotyledons,  Spaditiflorce,  is  a 
very  large  one,  and  includes  the  largest  and  the  smallest  plants 
of  the  whole  sub-class.  In  all  of  them  the  flowers  are  small 
and  often  very  inconspicuous ;  usually,  though  not  always, 
the  male  and  female  flowers  are  separate,  and  often  on  dif- 
ferent plants.  The  smallest  members  of  the  group  are  little 
aquatics,  scarcely  visible  to  the  naked  eye,  and  of  extremely 
simple  structure,  but  nevertheless  these  little  plants  produce 
true  flowers.  In  marked  contrast  to  these  are  the  palms,  some 
of  which  reach  a  height  of  thirty  metres  or  more. 

The  flowers  in  most  of  the  order  are  small  and  inconspicuous, 
but  aggregated  on  a  spike  (spadix)  which  may  be  of  very  large 
size.  Good  types  of  the  order  are  the  various  aroids  (Aroidece)j 
of  which  the  calla  (Richardia)  is  a  very  familiar  cultivated 
example.  Of  wild  forms  the  sweet-flag  (Acorus),  Jack-in-the- 
pulpit  (Ariscema)  (Fig.  86,  A}  Z>),  skunk-cabbage  (Symplocar- 
pus)j  and  wild  calla  may  be  noted.  In  Ariscema  (Fig.  86,  A) 
the  flowers  are  borne  only  on  the  base  of  the  spadix,  and  the 
plant  is  dioecious.  The  flowers  are  of  the  simplest  structure, 
the  female  consisting  of  a  single  carpel,  and  the  male  of  four 


158 


BOTANY. 


stamens  ((7,  D).  While  the  individual  flowers  are  destitute 
of  a  perigone,  the  whole  inflorescence  (cluster  of  flowers)  is 
surrounded  by  a  large  leaf  (spathe),  which  sometimes  is  bril- 


FIG.  86.  —  Types  of  Spadiciflorse.  A,  inflorescence  of  Jack-in-the-pulpit 
(Arissema,  AroidesR).  The  flowers  (fl.)  are  at  the  base  of  a  spike  (spadix), 
surrounded  by  a  sheath  (spathe),  which  has  been  cut  away  on  one  side  in 
order  to  show  the  flowers,  x  y2.  B,  leaf  of  the  same  plant,  x  y4.  C,  vertical 
section  of  a  female  flower,  x  2.  D,  three  male  flowers,  each  consisting  of 
four  stamens,  x  2.  E,  two  plants  of  a  duck-weed  (Lemna),  the  one  at  the 
left  is  in  flower,  x  4.  F,  another  common  species.  L,  Trisnlca,  x  l.  G, 
male  flower  of  E,  x  25.  H,  optical  section  of  the  female  flower,  showing  the 
single  ovule  (o?>.),  x  25.  /,  part  of  the  inflorescence  of  the  bur-reed  (tipar- 
yanium),  with  female  flowers,  x  %  (Tj/phacese).  J,  a  single,  female  flower, 
x  2.  K,  a  ripe  fruit,  x  1.  L,  longitudinal  section  of  the  same.  M,  two  male 
flowers,  x  1.  N,  a  pond-weed  (Potomoc/eton) ,  x  1  (Naiadacesz) .  O,  a  single 
flower,  x  2,  P,  the  same,  with  the  perianth  removed,  x  2.  Q,  fruit  of  the 
3,  x  2. 


liantly  colored,  this  serving  to  attract  insects.  The  leaves  of 
the  aroids  are  generally  large  and  sometimes  compound,  the 
only  instance  of  true  compound  leaves  among  the  monocoty- 
ledons (Fig.  86,  B). 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      159 

Probably  to  be  regarded  as  reduced  aroids  are  the  duck- 
weeds (Lemnacece)  (Fig.  86,  F,  H\  minute  floating  plants 
without  any  differentiation  of  the  plant  body  into  stem  and 
leaves.  They  are  globular  or  discoid  masses  of  cells,  most  of 
them  having  roots  ;  but  one  genus  (  Wolffia)  has  no  roots  nor 
any  trace  of  fibre-vascular  bundles.  The  flowers  are  reduced 
to  a  single  stamen  or  carpel  (Figs.  E,  G,  H). 

The  cat-tail  (Typha)  and  bur-reed  (Sparganium)  (Fig.  86, 
7,  L)  are  common  representatives  of  the  family  Typhcicece, 
and  the  pond-weeds  (Naias  and  Potomogeton)  are  common  ex- 
amples of  the  family  Naiadece.  These  are  aquatic  plants, 
completely  submerged  (Naias),  or  sometimes  partially  floating 
(Potomogeton).  The  latter  genus  includes  a  number  of  species 
with  leaves  varying  from  linear  (very  narrow  and  pointed)  to 
broadly  oval,  and  are  everywhere  common  in  slow  streams. 

The  largest  members  of  the  group  are  the  screw-pines  (Pan- 
danew)  and  the  palms  (Palmce).  These  are  represented  in  the 
United  States  by  only  a  few  species  of  the  latter  family,  con- 
fined to  the  southern  and  southwestern  portions.  The  palmet- 
toes  (Sabal  and  Chamcerops)  are  the  best  known. 

Both  the  palms  and  screw-pines  are  often  cultivated  for 
ornament,  and  as  is  well  known,  in  the  warmer  parts  of  the 
world  the  palms  are  among  the  most  valuable  of  all  plants. 
The  date  palm  (Phoenix  dactylifera)  and  the  cocoanut  (Cocos 
nucifera)  are  the  best  known.  The  apparently  compound 
("pinnate"  or  feather-shaped)  leaves  of  many  palms  are  not 
strictly  compound ;  that  is,  they  do  not  arise  from  the  branching 
of  an  originally  single  leaf,  but  are  really  broad,  undivided 
leaves,  which  are  closely  folded  like  a  fan  in  the  bud,  and  tear 
apart  along  the  folds  as  the  leaf  opens. 

Although  these  plants  reach  such  a  great  size,  an  examina- 
tion of  the  stem  shows  that  it  is  built  on  much  the  same  plan 
as  that  of  the  other  monocotyledons ;  that  is,  the  stem  is  com- 
posed of  a  mass  of  soft,  ground  tissue  through  which  run  many 
small  isolated,  fibro-vascular  bundles.  A  good  idea  of  this 


160 


BOTANY, 


structure  may  be  had  by  cutting  across  a  corn-stalk,  which  is 
built  on  precisely  the  same  pattern. 

ORDER  IV.  —  Glumacece. 

The  plants  of  this  order  resemble  each  other  closely  in  their 
habit,  all  having  long,  narrow  leaves  with  sheathing  bases  that 
D 

r- t 


FIG.  87.  —  Types  of  Glumacese.  A,  a .sedge,  Carex  (Cyperacese) .  d1,  the  male; 
? ,  the  female  flowers,  x  %.  B,  a  single  male  flower,  x  2.  C,  a  female  flower, 
x  2.  D,  fruiting  spike  of  another  Carex,  x  %.  E,  a  single  fruit,  x  l.  F,  the 
same,  with  the  outer  envelope  removed,  and  slightly  enlarged.  G,  section  of 
F,  x  3.  em.  the  embryo.  H,  a  bulrush,  Scirpus  (Cyperacese),  x  %.  /,  a 
single  spikelet,  x  2.  J,  a  single  flower,  x  3.  K,  a  spikelet  of  flowers  of  the 
common  orchard  grass,  Dactylis  (Graminese),  x  2.  L,  a  single  flower,  x  2. 
M,  the  base  of  a  leaf,  showing  the  split  sheath  encircling  the  stem,  x  1.  N, 
section  of  a  kernel  of  corn,  showing  the  embryo  (em.),  x  2. 

surround  the  slender,  distinctly  jointed  stem  which  frequently 
has  a  hard,  polished  surface.  The  flowers  are  inconspicuous, 
borne  usually  in  close  spikes,  and  destitute  of  a  perigone  or 
having  this  reduced  to  small  scales  or  hairs.  The  flowers  are 
usually  surrounded  by  more  or  less  dry  leaves  (glumes,  palese) 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      161 

which  are  closely  set,  so  as  to  nearly  conceal  the  flowers.  The 
flowers  are  either  hermaphrodite  or  unisexual. 

There  are  two  well-marked  families,  the  sedges  (Cyperace*ce) 
and  the  grasses  (Graminece).  The  former  have  solid,  often 
triangular  stems,  and  the  sheath  at  the  base  of  the  leaves  is 
not  split.  The  commonest  genera  are  Carex  (Fig.  87,  A,  G) 
and  Cyperus,  of  which  there  are  many  common  species,  differ- 
ing very  little  and  hard  to  distinguish.  There  are  several 
common  species  of  Carex  which  blossom  early  in  the  spring, 
the  male  flowers  being  quite  conspicuous  on  account  of  the 
large,  yellow  anthers.  The  female  flowers  are  in  similar  spikes 
lower  down,  where  the  pollen  readily  falls  upon  them,  and  is 
caught  by  the  long  stigmas.  In  some  other  genera,  e.g.  the  bul- 
rushes (Scirpus)  (Fig.  87,  H),  the  flowers  are  hermaphrodite, 
i.e.  contain  both  stamens  and  pistils.  The  fruit  (Fig.  87,  F) 
is  seed-like,  but  really  includes  the  wall  of  the  ovary  as  well, 
which  is  grown  closely  to  the  enclosed  seed.  The  embryo  is 
small,  surrounded  by  abundant  endosperm  (Fig.  87,  G).  Very 
few  of  the  sedges  are  of  any  economic  importance,  though  one, 
the  papyrus  of  Egypt,  was  formerly  much  valued  for  its  pith, 
which  was  manufactured  into  paper. 

The  second  family,  the  grasses,  on  the  contrary,  includes 
the  most  important  of  all  food  plants,  all  of  the  grains  belong- 
ing here.  They  differ  mainly  from  the*  sedges  in  having,  gen- 
erally, hollow,  cylindrical  stems,  and  the  sheath  of  the  leaves 
split  down  one  side ;  the  leaves  are  in  two  rows,  while  those 
of  the  sedges  are  in  three.  The  flowers  (Fig.  87,  L)  are 
usually  perfect ;  the  stigmas,  two  in  number  and  like  plumes, 
so  that  they  readily  catch  the  pollen  which  is  blown  upon 
them.  A  few,  like  the  Indian  corn,  have  the  flowers  unisexual ; 
the  male  flowers  are  at  the  top  of  the  stem  forming  the 
"  tassel,"  and  the  female  flowers  lower  down  forming  the  ear. 
The  "  silk "  is  composed  of  the  enormously  lengthened  stigmas. 
The  fruits  resemble  those  of  the  sedges,  but  the  embryo  is 
usually  larger  and  placed  at  one  side  of  the  endosperm  (N,  em.), 


162 


BOTANY. 


While  most  of  the  grasses  are  comparatively  small  plants, 
a  few  of  them  are  almost  tree-like  in  their  proportions,  the 
species  of  bamboo  (Bambusa)  sometimes  reaching  a  height  of 
twenty  to  thirty  metres,  with  stems  thirty  to  forty  centimetres 
in  diameter. 


ORDER  V.  —  Scitaminece. 

The  plants  of  this  order  are  all  inhabitants  of  the  warmer 
parts  of  the  earth,  and  only  a  very  few  occur  within  the  limits 
of  the  United  States,  and  these  confined  to  the  extreme  south. 


n 


FIG.  88.  —  Scitaminess.  A,  upper  part  of  a  flowering  plant  of  Indian  shot 
(Canna),  much  reduced  in  size  (Cannacete).  B,  a  single  flower,  x  V2.  C,  the 
single  stamen  (an.),  and  petal-like  pistil  (#?/.)>  x  1.  D,  section  of  the  ovary, 
x  2.  E,  diagram  of  the  flower.  The  place  of  the  missing  stamens  is  indi- 
cated by  small  circles.  F,  fruit,  x  %.  G,  section  of  an  unripe  seed.  em. 
embryo,  p,  perisperm,  x  2. 

They  are  extremely  showy  plants,  owing  to  their  large  leaves 
and  brilliant  flowers,  and  for  this  reason  are  cultivated  exten- 
sively. Various  species  of  Canna  (Fig.  88)  are  common  in 
gardens,  where  they  are  prized  for  their  large,  richly-colored 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      163 

leaves,  and  clusters  of  scarlet,  orange,  or  yellow  flowers.  The 
leafy  stems  arise  from  thick  tubers  or  root  stocks,  and  grow 
rapidly  to  a  height  of  two  metres  or  more  in  the  larger  species. 
The  leaves,  as  in  all  the  order,  are  very  large,  and  have  a  thick 
midrib  with  lateral  veins  running  to  the  margin.  The  young 
leaves  are  folded  up  like  a  trumpet.  The  flowers  are  irregular 
in  form,  and  in  Canna  only  a  single  stamen  is  found  ;  or  if  more 
are  present,  they  are  reduced  to  petal-like  rudiments.  The 
single,  perfect  stamen  (Fig.  88,  C,  an.)  has  the  filament  broad 
and  colored  like  the  petals,  and  the  anther  attached  to  one  side. 
The  pistil  (gy,)  is  also  petal-like.  There  are  three  circles  of 
leaves  forming  the  perigone,  the  two  outer  being  more  or  less 
membranaceous,  and  only  the  three  inner  petal-like  in  texture. 
The  ovary  (o)  is  inferior,  and  covered  on  the  outside  with 
little  papillae  that  afterward  form  short  spines  on  the  outside 
of  the  fruit  (F). 

The  seeds  are  large,  but  the  embryo  is  very  small.  A  sec- 
tion of  a  nearly  ripe  seed  shows  the  embryo  (em.)  occupying 
the  upper  part  of  the  embryo  sac  which  does  not  nearly  fill 
the  seed  and  contains  no  endosperm.  The  bulk  of  the  seed  is 
derived  from  the  tissue  of  the  body  of  the  ovule,  which  in  most 
seeds  becomes  entirely  obliterated  by  the  growth  of  the  embryo 
sac.  The  cells  of  this  tissue  become  filled  with  starch,  and 
serve  the  same  purpose  as  the  endosperm  of  other  seeds.  This 
tissue  is  called  "  perisperm." 

Of  food  plants  belonging  to  this  order,  the  banana  (Musa) 
is  much  the  most  important.  Others  of  more  or  less  value  are 
species  of  arrowroot  (Maranta)  and  ginger  (Zingiber). 

There  are  three  families :  I.  Musacece  (banana  family) ; 
II.  Zingiberacece  (ginger  family) ;  and  III.  Cannacece,  (Canna, 
Maranta) . 

ORDER  VI.  —  Gynandrce. 

By  far  the  greater  number  of  the  plants  of  this  order  belong 
to  the  orchis  family  (Orchidece),  the  second  family  of  the  order 


164 


BOTANY. 


(Apostasiece) ,  being  a  small  one  and  unrepresented  in  the 
United  States.  The  orchids  are  in  some  respects  the  most 
highly  specialized  of  all  flowers,  and  exhibit  wonderful  variety 
in  the  shape  and  color  of  the  flowers,  which  are  often  of 
extraordinary  beauty,  and  show  special  contrivances  for  cross- 
fertilization  that  are  without  parallel  among  flowering  plants. 


FIG.  89.  —  Gynandrs&.  A,  inflorescence  of  the  showy  orchis  (Orchis  spectabilis) , 
x  1  (Orchidese).  B,  a  single  flower,  with  the  upper  leaves  of  the  perianth 
turned  back  to  show  the  column  (x).  sp.  the  spur  attached  to  the  lower 
petal  or  lip.  o,  the  ovary,  x  1.  C,  the  column  seen  from  in  front,  an.  the 
stamen,  gy.  the  stigmatic  surface,  x  1.  D,  the  two  pollen  masses  attached 
to  a  straw,  which  was  inserted  into  the  flower,  by  means  of  the  viscid  disc  (d) : 
i,  the  masses  immediately  after  their  withdrawal ;  n,  in,  the  same  a  few 
minutes  later,  showing  the  change  in  position.  E,  diagram  of  the  flower ; 
the  position  of  the  missing  stamens  indicated  by  small  circles. 

The  flowers  are  always  more  or  less  bilaterally  symmetrical 
(zygomorphic).  The  ovary  is  inferior,  and  usually  twisted 
so  as  to  turn  the  flower  completely  around.  There  are  two 
sets  of  perigone  leaves,  three  in  each,  and  these  are  usually 
much  alike  except  the  lower  (through  the  twisting  of  the 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      165 


ovary)  of  the  inner  set.  This  petal,  known  as  the  "lip"  or 
"labellum,"  is  usually  larger  than  the  others,  and  different 
in  color,  as  well  as  being  frequently  of  peculiar  shape.  In 
many  of  them  it  is  also  prolonged  backward  in  a  hollow  spur 
(see  Tig.  89,  B) .  In  all  of  the  orchids  except  the  lady's-slippers 
(Cypripedium)  (Fig.  90,  B),  only  one  perfect  stamen  is  devel- 
oped, and  this  is  united  with  the  three  styles  to  form  a  special 

D 


FIG.  90.  —  Forms  of  Orchidese. 


x  1.    B,  yellow 


A,  putty-root  (Aplectrum) , 

lady's-slipper  (Cypripediurri) ,  x  %.  C,  the  column  of  the  same,  x  l.  an. 
one  of  the  two  perfect  stamens,  st.  sterile,  petal-like  stamen,  gy.  stigma. 
D,  Arethusa,  x  %.  E,  section  of  the  column,  x  l.  an.  stamen,  gy.  stigma. 
F,  the  same,  seen  from  in  front.  G,  Habenaria,  x  1.  H,  Calopogon,  x  1.  In 
the  last  the  ovary  is  not  twisted,  so  that  the  lip  (L)  lies  on  the  upper  side  of 
the  flower. 

structure  known  as  the  "column"  or  " gynostemium "  (Fig. 
89,  B,  C).  The  pollen  spores  are  usually  aggregated  into  two 
or  four  waxy  masses  ("  pollinia,"  sing,  pollinium),  which  usually 
can  only  be  removed  by  the  agency  of  insects  upon  which  all 
but  a  very  few  orchids  are  absolutely  dependent  for  the  pollina- 
tion of  the  flowers. 


166  BOTANY. 

In  the  lady-slippers  there  are  two  fertile  stamens,  and  a 
third  sterile  one  has  the  form  of  a  large  triangular  shield  ter- 
minating the  column  (Fig.  90,  C,  st. ) . 

The  ovules  of  the  orchids  are  extremely  small,  and  are  only 
partly  developed  at  the  time  the  flower  opens,  the  pollen  tube 
growing  very  slowly  and  the  ovules  maturing  as  it  grows  down 
through  the  tissues  of  the  column.  The  ripe  seeds  are  exces- 
sively numerous,  but  so  fine  as  to  look  like  dust. 

The  orchids  are  mostly  small  or  moderate-sized  plants,  few 
of  them  being  more  than  a  metre  or  so  in  height.  All  of  our 
native  species,  with  the  exception  of  a  few  from  the  extreme 
south,  grow  from  fibrous  roots  or  tubers,  but  many  tropical 
orchids,  as  is  well  known,  are  "  epiphytes  "  ;  that  is,  they  grow 
upon  the  trunks  and  branches  of  trees.  One  genus,  Vanilla,  is 
a  twining  epiphyte ;  the  fruit  of  this  plant  furnishes  the 
vanilla  of  commerce.  Aside  from  this  plant,  the  economical 
value  of  the  orchids  is  small,  although  a  few  of  them  are  used 
medicinally,  but  are  not  specially  valuable. 

Of  the  five  thousand  species  known,  the  great  majority  are 
inhabitants  of  the  tropics,  but  nevertheless  there  are  within 
the  United  States  a  number  of  very  beautiful  forms.  The 
largest  and  showiest  are  the  lady's-slippers,  of  which  we 
have  six  species  at  the  north.  The  most  beautiful  is  the 
showy  lady's-slipper  (Cypripedium  spectabile),  whose  large,  pink 
and  white  flowers  rival  in  beauty  many  of  the  choicest  tropical 
orchids.  Many  of  the  Habenarias,  including  the  yellow  and 
purple  fringed  orchids,  are  strikingly  beautiful  as  are  the 
Aretliusece,  (Arethusa,  Pogonia,  Calopogon).  The  last  of  these 
(Fig.  90,  H)  differs  from  all  our  other  native  orchids  in  having 
the  ovary  untwisted  so  that  the  labellum  lies  on  the  upper 
side  of  the  flower. 

A  number  of  the  orchids  are  saprophytic,  growing  in  soil 
rich  in  decaying  vegetable  matter,  and  these  forms  are  often 
nearly  or  quite  destitute  of  chlorophyll,  being  brownish  or 
yellowish  in  color,  and  with  rudimentary  leaves.  The  coral 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      167 

roots  (Corallorhiza) ,  of  which  there  are  several  species,  are 
examples  of  these,  and  another  closely  related  form,  the  putty- 
root  (Aplectrum)  (Fig.  90,  A),  has  the  flowering  stems  like 
those  of  Corallorhiza,  but  there  is  a  single,  large,  plaited  leaf 
sent  up  later. 

ORDER  VII.  —  Helobice. 

The  last  order  of  the  monocotyledons  is  composed  of  marsh 
or  water  plants,  some  of  which  recall  certain  of  the  dicotyledons. 
Of  the  three  families,  the  first,  Juncaginece,  includes  a  few  in- 
conspicuous plants  with  grass-like  or  rush-like  leaves,  and  small, 
greenish  or  yellowish  flowers  (e.g.  arrow-grass,  Triglochin). 

The  second  family  (Alismacece)  contains  several  large  and 
showy  species,  inhabitants  of  marshes.  Of  these  the  water- 
plantain  (Alisma),  a  plant  with  long-stalked,  oval,  ribbed 
leaves,  and  a  muth-branched  panicle  of  small,  white  flowers, 
is  very  common  in  marshes  and  ditches,  and  the  various 
species  of  arrowhead  (Sagittaria)  are  among  the  most  charac- 
teristic of  our  marsh  plants.  The  flowers  are  unisexual ;  the 
female  flowers  are  usually  borne  at  the  base  of  the  inflores- 
cence, and  the  male  flowers  above.  The  gynoecium  (Fig.  91,  JB) 
consists  of  numerous,  separate  carpels  attached  to  a  globular 
receptacle.  The  sepals  are  green  and  much  smaller  than  the 
white  petals.  The  leaves  (F)  are  broad,  and,  besides  the 
thickened,  parallel  veins,  have  numerous  smaller  ones  connect- 
ing these. 

The  last  family  is  the  Hydrocharidece.  They  are  submersed 
aquatics,  or  a  few  of  them  with  long-stalked,  floating  leaves. 
Two  forms,  the  ditch-moss  (Elodea)  (Fig.  91,  G,  I)  and  eel- 
grass  (Vallisneria)  are  very  common  in  stagnant  or  slow- 
running  water.  In  both  of  these  the  plants  are  completely 
submersed,  but  there  is  a  special  arrangement  for  bringing 
the  flowers  to  the  surface  of  the  water.  Like  the  arrowhead, 
the  flowers  are  unisexual,  but  borne  on  different  plants.  The 
female  flowers  (H,  L)  are  comparatively  large,  especially 


168 


BOTANY. 


in  Vallisneriaj  and  are  borne  on  long  stalks,  by  means  of  which 
they  reach  the  surface  of  the  water,  where  they  expand  and 
are  ready  for  pollination.  The  male  flowers  (Fig.  91,  J,  K} 
are  extremely  small  and  borne,  many  together,  surrounded 
by  a  membranous  envelope,  the  whole  inflorescence  attached 


FIG.  91.  —  Types  of  Helobise.  A,  inflorescence  of  arrow-head  (Sagittaria), 
with  a  single  female  flower,  x  %  (Alismacese).  B,  section  through  the 
gynoecium,  showing  the  numerous  single  carpels,  x  3.  C,  a  ripe  fruit,  x  3. 
I),  a  male  flower,  x  i.  E,  a  single  stamen,  x  3.  F,  a  leaf  of  Sagittaria 
variabilis,  x  v6.  G,  ditch-moss  (Elodea),  with  a  female  flower  (fl.),  x  %. 
(Hydrocharidese).  H,  the  flower,  x  2.  an.  the  rudimentary  stamens,  st.  the 
stigma.  /,  cross-section  of  the  ovary,  x  4.  J,  male  inflorescence  of  eel-grass 
(Vallisneria} ,  x  l.  K,  a  single  expanded  male  flower,  x  12.  st. the  stamen. 
i,  a  female  flower,  x  1.  gy.  the  stigma. 

by  a  short  stalk.  When  the  flowers  are  ready  to  open,  they 
break  away  from  their  attachment,  and  the  envelope  opens, 
allowing  them  to  escape,  and  they  immediately  rise  to  the 
surface  where  they  expand  and  collect  in  great  numbers  about 
the  open  female  flowers.  Sometimes  these  are  so  abundant 


CLASSIFICATION   OF  THE  MONOCOTYLEDONS.      169 

during  the  flowering  period  (late  in  summer)  that  the  surface 
of  the  water  looks  as  if  flour  had  been  scattered  over  it.  After 
pollination  is  effected,  the  stem  of  the  female  flower  coils  up 
like  a  spring,  drawing  the  flower  beneath  the  water  where  the 
fruit  ripens. 

The  cells  of  these  plants  show  very  beautifully  the  circula- 
tion of  the  protoplasm,  the  movement  being  very  marked  and 
continuing  for  a  long  time  under  the  microscope.  To  see  this 
the  whole  leaf  of  Elodea,  or  a  section  of  that  of  Vallisneria, 
may  be  used. 


CHAPTER   XVII. 

DICOTYLEDONS. 

THE  second  sub-class  of  the  angiosperms,  the  dicotyledons, 
receive  their  name  from  the  two  opposite  seed  leaves  or  coty- 
ledons with  which  the  young  plant  is  furnished.  These  leaves 
are  usually  quite  different  in  shape  from  the  other  leaves,  and 
not  infrequently  are  very  thick  and  fleshy,  filling  nearly  the 
whole  seed,  as  may  be  seen  in  a  bean  or  pea.  The  number  of 
the  dicotyledons  is  very  large,  and  very  much  the  greater  num- 
ber of  living  spermaphytes  belong  to  this  group.  They  exhibit 
much  greater  variety  in  the  structure  of  the  flowers  than  the 
monocotyledons,  and  the  leaves,  which  in  the  latter  are  with  few 
exceptions  quite  uniform  in  structure,  show  here  almost  infinite 
variety.  Thus  the  leaves  may  be  simple  (undivided)  ;  e.g.  oak, 
apple  ;  or  compound,  as  in  clover,  locust,  rose,  columbine,  etc. 
The  leaves  may  be  stalked  or  sessile  (attached  directly  to  the 
stem),  or  even  grown  around  the  stem,  as  in  some  honeysuckles. 
The  edges  of  the  leaves  may  be  perfectly  smooth  ("  entire  "),  or 
they  may  be  variously  lobed,  notched,  or  wavy  in  many  ways. 
As  many  of  the  dicotyledons  are  trees  or  shrubs  that  lose 
their  leaves  annually,  special  leaves  are  developed  for  the  pro- 
tection of  the  young  leaves  during  the  winter.  These  have 
the  form  of  thick  scales,  and  often  are  provided  with  glands 
secreting  a  gummy  substance  which  helps  render  them  water- 
proof. These  scales  are  best  studied  in  trees  with  large, 
winter  buds,  such  as  the  horsechestnut  (Fig.  92),  hickory, 
lilac,  etc.  On  removing  the  hard,  scale  leaves,  the  delicate, 
young  leaves,  and  often  the  flowers,  may  be  found  within  the 
bud.  If  we  examine  a  young  shoot  of  lilac  or  buck-eye,  just 
as  the  lenvcs  are  expanding  in  the  spring,  a  complete  series  of 
170 


DICOTYLEDONS. 


171 


forms  may  be  seen  from  the  simple,  external  scales,  through 
immediate  forms,  to  the  complete  foliage  leaf.  The  veins  of 
the  leaves  are  almost  always  much-branched,  the  veins  either 
being  given  off  from  one  main  vein  or  midrib  (feather-veined 
or  pinnate-veined),  as  in  an  apple  leaf,  or  there  may  be  a 
number  of  large  veins  radiating  from  the  base  of  the  leaf,  as 
in  the  scarlet  geranium  or  mallow.  Such  leaves  are  said  to 
be  palmately  veined. 

Some  of  them  are  small  her- 
baceous plants,  either  upright 
or  prostrate  upon  the  ground, 
over  which  they  may  creep 
extensively,  becoming  rooted 
at  intervals,  as  in  the  white 
clover,  or  sending  out  special 


runners,    as    is     seen    in    the 


strawberry.  Others  are  woody 
stemmed  plants,  persisting  from 
year  to  year,  and  often  becom- 
ing great  trees  that  live  for  hun- 
dreds of  years.  Still  others  are 
climbing  plants,  either  twining 
their  stems  about  the  support, 
like  the  morning-glory,  hop, 
honeysuckle,  and  many  others, 
or  having  special  organs  (ten- 
drils) by  which  they  fasten 
themselves  to  the  support. 

These  tendrils  originate  in  different  ways.  Sometimes,  as  in 
the  grape  and  Virginia  creeper,  they  are  reduced  branches,  either 
coiling  about  the  support,  or  producing  little  suckers  at  their 
tips  by  which  they  cling  to  walls  or  the  trunks  of  trees. 
Other  tendrils,  as  in  the  poison  ivy  and  the  true  ivy,  are  short 
roots  that  fasten  themselves  firmly  in  the  crevices  of  bark  or 
stones.  Still  other  tendrils,  as  those  of  the  sweet-pea  and 
clematis,  are  parts  of  the  leaf. 


FIG.  92.  — End  of  a  branch  of  a 
horsechestnut  in  winter,  show- 
ing the  buds  covered  by  the  thick, 
brown  scale  leaves,  x  l. 


172 


BOTANY. 


The  steins  may  be  modified  into  thorns  for  protection,  as  we 
see  in  many  trees  and  shrubs,  and  parts  of  leaves  may  be  simi- 
larly changed,  as  in  the  thistle.  The  underground  steins  often 
become  much  changed,  forming  bulbs,  tubers,  root  stocks,  etc. 


FIG.  93.  —  A,  base  of  a  plant  of  shepherd 's-purse  (Capsellabursa-pastoris), 
x  %.  r,  the  main  root.  B,  upper  part  of  the  inflorescence,  x  1.  C,  two 
leaves:  i,  from  the  upper  part;  n,  from  the  base  of  the  plant,  x  1.  D,  a 
flower,  x  3.  E,  the  same,  with  sepals  and  petals  removed,  x  3.  F,  petal.  G, 
sepal.  H,  stamen,  x  10.  /,  filament,  an.  anther.  /,  a  fruit  with  one  of  the 
valves  removed  to  show  the  seeds,  x  4.  J,  longitudinal  section  of  a  seed, 
x  8.  K,  the  embryo  removed  from  the  seed,  x  8.  I,  the  first  leaves  (coty- 
ledons), st.  the  stem  ending  in  the  root.  L,  cross-section  of  the  stem,  x  20. 
/&.  fibro-vascular  bundle.  M,  a  similar  section  of  the  main  root,  x  15.  N, 
diagram  of  the  flower. 

much  as  in  the  monocotyledons.  These  structures  are  espe- 
cially found  in  plants  which  die  down  to  the  ground  each  year, 
and  contain  supplies  of  nourishment  for  the  rapid  growth  of 
the  annual  shoots. 

The  structure   of  the  tissues,  and  the  peculiarities   of  the 
flower  and  fruit,  will  be  better  understood  by  a  somewhat  care- 


DICOTYLEDONS.  173 

ful  examination  of  a  typical  dicotyledon,  and  a  comparison 
with  this  of  examples  of  the  principal  orders  and  families. 

One  of  the  commonest  of  weeds,  and  at  the  same  time  one 
of  the  most  convenient  plants  for  studying  the  characteristics 
of  the  dicotyledons,  is  the  common  shepherd' s-purse  (Oapsella 
bursa-pastoris)  (Figs.  93-95). 

The  plant  grows  abundantly  in  waste  places,  and  is  in  flower 
nearly  the  year  round,  sometimes  being  found  in  flower  in 
midwinter,  after  a  week  or  two  of  warm  weather.  It  is,  how- 
ever, in  best  condition  for  study  in  the  spring  and  early 
summer.  The  plant  may  at  once  be  recognized  by  the  heart- 
shaped  pods  and  small,  white,  four-petaled  flowers.  The  plant 
begins  to  flower  when  very  small,  but  continues  to  grow  until 
it  forms  a  much-branching  plant,  half  a  metre  or  more  in 
height.  On  pulling  up  the  plant,  a  large  tap-root  (Fig.  93,  A,  r) 
is  seen,  continuous  with  the  main  stem  above  ground.  The 
first  root  of  the  seedling  plant  continues  here  as  the  main  root 
of  the  plant,  as  was  the  case  with  the  gymnosperms,  but  not 
with  the  monocotyledons.  From  this  tap-root  other  small  ones 
branch  off,  and  these  divide  repeatedly,  forming  a  complex 
root  system.  The  main  root  is  very  tough  and  hard,  owing  to 
the  formation  of  woody  tissue  in  it.  A  cross-section  slightly 
magnified  (Fig.  93,  M ),  shows  a  round,  opaque,  white,  central 
area  (#),  the  wood,  surrounded  by  a  more  transparent,  irregu- 
lar ring  (ph.),  the  phloem  or  bast;  and  outside  of  this  is  the 
ground  tissue  and  epidermis. 

The  lower  leaves  are  crowded  into  a  rosette,  and  are  larger 
than  those  higher  up,  from  which  they  differ  also  in  having 
a  stalk  (petiole),  while  the  upper  leaves  are  sessile.  The 
outline  of  the  leaves  varies  much  in  different  plants  and  in 
different  parts  of  the  same  plant,  being  sometimes  almost 
entire,  sometimes  divided  into  lobes  almost  to  the  midrib,  and 
between  these  extremes  all  gradations  are  found.  The  larger 
leaves  are  traversed  by  a  strong  midrib  projecting  strongly  on 
the  lower  side  of  the  leaf,  and  from  this  the  smaller  veins 


174  BOTANY. 

branch.  The  upper  leaves  have  frequently  two  smaller  veins 
starting  from  the  base  of  the  leaf,  and  nearly  parallel  with 
the  midrib  (C  i).  The  surface  of  the  leaves  is  somewhat 
roughened  with  hairs,  some  of  which,  if  slightly  magnified, 
look  like  little  white  stars. 

Magnifying  slightly  a  thin  cross-section  of  the  stem,  it 
shows  a  central,  ground  tissue  (pith),  whose  cells  are  large 
enough  to  be  seen  even  when  very  slightly  enlarged.  Sur- 
rounding this  is  a  ring  of  fibro-vascular  bundles  (L,  /&.), 
appearing  white  and  opaque,  and  connected  by  a  more  trans- 
parent tissue.  Outside  of  the  ring  of  fibro-vascular  bundles 
is  the  green  ground  tissue  and  epidermis.  Comparing  this 
with  the  section  of  the  seedling  pine  stem,  a  resemblance  is 
at  once  evident,  and  this  arrangement  was  also  noticed  in  the 
stem  of  the  horse-tail. 

Branches  are  given  off  from  the  main  stem,  arising  at  the 
point  where  the  leaves  join  the  stem  (axils  of  the  leaves), 
and  these  may  in  turn  branch.  All  the  branches  terminate 
finally  in  an  elongated  inflorescence,  and  the  separate  flowers  are 
attached  to  the  main  axis  of  the  inflorescence  by  short  stalks. 
This  form  of  inflorescence  is  known  technically  as  a  "raceme." 
Each  flower  is  really  a  short  branch  from  which  the  floral 
leaves  arise  in  precisely  the  same  way  as  the  foliage  leaves  do 
from  the  ordinary  branches.  There  are  five  sets  of  floral 
leaves:  I.  four  outer  perigone  leaves  (sepals)  (F),  small, 
green,  pointed  leaves  traversed  by  three  simple  veins,  and 
together  forming  the  calyx;  II.  four  larger,  white,  inner 
perigone  leaves  (petals)  (6r),  broad  and  slightly  notched  at 
the  end,  and  tapering  to  the  point  of  attachment.  The  petals 
collectively  are  known  as  the  "corolla."  The  veins  of  the 
petals  fork  once ;  III.  and  IV.  two  sets  of  stamens  (E),  the 
outer  containing  two  short,  and  the  inner,  four  longer  ones 
arranged  in  pairs.  Each  stamen  has  a  slender  filament  (H}  /) 
and  a  two-lobed  anther  (an.).  The  innermost  set  consists  of 
two  carpels  united  into  a  compound  pistil.  The  ovary  is 


DICOTYLEDONS.  175 

oblong,  slightly  flattened  so  as  to  be  oval  in  section,  and 
divided  into  two  chambers.  The  style  is  very  short  and  tipped 
by  a  round,  flattened  stigma. 

The  raceme  continues  to  grow  for  a  long  time,  forming  new 
flowers  at  the  end,  so  that  all  stages  of  flowers  and  fruit  may 
often  be  found  in  the  same  inflorescence. 

The  flowers  are  probably  quite  independent  of  insect  aid  in 
pollination,  as  the  stamens  are  so  placed  as  to  almost  infalli- 
bly shed  their  pollen  upon  the  stigma.  This  fact,  probably, 
accounts  for  the  inconspicuous  character  of  the  flowers. 

After  fertilization  is  effected,  and  the  outer  floral  leaves  fall 
off,  the  ovary  rapidly  enlarges,  and  becomes  heart-shaped  and 
much  flattened  at  right  angles  to  the  partition.  When  ripe, 
each  half  falls  away,  leaving  the  seeds  attached  by  delicate 
stalks  (f uniculi,  sing,  funiculus)  to  the  edges  of  the  membranous 
partition.  The  seeds  are  small,  oval  bodies  with  a  shining, 
yellow-brown  shell,  and  with  a  little  dent  at  the  end  where 
the  stalk  is  attached.  Carefully  dividing  the  seed  lengthwise, 
or  crushing  it  in  water  so  as  to  remove  the  embryo,  we  find 
it  occupies  the  whole  cavity  of  the  seed,  the  young  stalk  (st.) 
being  bent  down  against  the  back  of  one  of  the  cotyledons  (/). 

A  microscopic  examination  of  a  cross-section  of  the  older  root  shows 
that  the  central  portion  is  made  up  of  radiating  Imes  of  thick-walled  cells 
(fibres)  interspersed  with  lines  of  larger,  round  openings  (vessels).  There 
is  a  ring  of  small  cambium  cells  around  this  merging  into  the  phloem, 
which  is  composed  of  irregular  cells,  with  pretty  thick,  but  soft  walls. 
The  ground  tissue  is  composed  of  large,  loose  cells,  which  in  the  older 
roots  are  often  ruptured  and  partly  dried  up.  The  epidermis  is  usually 
indistinguishable  in  the  older  roots.  To  understand  the  early  structure 
of  the  roots,  the  smallest  rootlets  obtainable  should  be  selected.  The 
smallest  are  so  transparent  that  the  tips  may  be  mounted  whole  in  water, 
and  will  show  very  satisfactorily  the  arrangement  of  the  young  tissues. 
The  tissues  do  not  here  arise  from  a  single,  apical  cell,  as  we  found  in  the 
pteridophytes,  but  from  a  group  of  cells  (the  shaded  cells  in  Fig.  94,  B). 
The  end  of  the  root,  as  in  the  fern,  is  covered  with  a  root  cap  (r)  com- 
posed of  successive  layers  of  cells  cut  off  from  the  growing  point.  The 
rest  of  the  root  shows  the  same  division  of  the  tissues  into  the  primary 


176 


BOTANY. 


epidermis  (dermatogen)  (d),  young  fibro- vascular  cylinder  (plerome) 
(j>Z.),  and  young  ground  tissue  (periblem)  (pb.).  The  structure  of  the 
older  portions  of  such  as  root  is  not  very  easy  to  study,  owing  to  dif- 
ficulty in  making  good  cross-sections  of  so  small  an  object.  By  using  a 
very  sharp  razor,  and  holding  perfectly  straight  between  pieces  of  pith, 
however,  satisfactory  sections  can  be  made.  The  cells  contain  so  much 
starch  as  to  make  them  almost  opaque,  and  potash  should  be  used  to  clear 


FIG.  94.  —  A,  cross-section  of  the  stem  of  the  shepherd's-purse,  including  a 
fibro-vascular  bundle,  x  150.  ep.  epidermis,  m,  ground  tissue,  sh.  bundle 
sheath,  ph.  phloem,  v.y.  xylem.  tr.  a  vessel.  B,  a  young  root  seen  in 
optical  section,  x  150.  r,  root  cap.  d,  young  epidermis,  pb.  ground.  pL 
young  fibro-vascular  bundle.  C,  cross  section  of  a  small  root,  x  150.  fb. 
fibre-vascular  bundle.  D,  epidermis  from  the  lower  side  of  the  leaf,  x  150. 
E,  a  star-shaped  hair  from  the  surface  of  the  leaf,  x  150.  F,  cross-section  of 
a  leaf,  x  150.  ep.  epidermis,  m,  ground  tissue,  fb.  section  of  a  vein. 

them.  The  fibro-vascular  bundle  is  of  the  radial  type,  there  "being  two 
masses  of  xylem  (xy.)  joined  in  the  middle,  and  separating  the  two 
phloem  masses  (p/t.),  some  of  whose  cells  are  rather  thicker  walled  than 
the  others.  The  bundle  sheath  is  not  so  plain  here  as  in  the  fern.  The 
ground  tissue  is  composed  of  comparatively  large  cells  with  thickish,  soft 
walls,  that  contain  much  starch.  The  epidermis  usually  dies  while  the 
root  is  still  young.  In  the  larger  roots  the  early  formation  of  the  cambium 


DICOTYLEDONS.  177 

ring,  and  the  irregular  arrangement  of  the  tissues  derived  from  its  growth, 
soon  obliterate  all  traces  of  the  primitive  arrangement  of  the  tissues. 
Making  a  thin  cross-section  of  the  stem,  and  magnifying  strongly,  we  find 
bounding  the  section  a  single  row  of  epidermal  cells  (Fig.  94,  A,  ep.) 
whose  walls,  especially  the  outer  ones,  are  strongly  thickened.  Within 
these  are  several  rows  of  thin- walled  ground- tissue  cells  containing  numer- 
ous small,  round  chloroplasts.  The  innermost  row  of  these  cells  (sh.) 
are  larger  and  have  but  little  chlorophyll.  This  row  of  cells  forms  a  sheath 
around  the  ring  of  fibro- vascular  bundles  very  much  as  is  the  case  in  the 
horse-tail.  The  separate  bundles  are  nearly  triangular  in  outline,  the 
point  turned  inward,  and  are  connected  with  each  other  by  masses  of 
fibrous  tissue  (/),  whose  thickened  walls  have  a  peculiar,  silvery  lustre. 
Just  inside  of  the  bundle  sheath  there  is  a  row  of  similar  fibres  marking 
the  outer  limit  of  the  phloem  (ph.).  The  rest  of  the  phloem  is  composed 
of  very  small  cells.  The  xylem  is  composed  of  fibrous  cells  with  yellow- 
ish walls  and  numerous  large  vessels  (tr.).  The  central  ground  tissue 
(pith)  has  large,  thin- walled  cells  with  numerous  intercellular  spaces,  as 
in  the  stem  of  Erythronium.  Some  of  these  cells  contain  a  few  scattered 
chloroplasts  in  the  very  thin,  protoplasmic  layer  lining  their  walls,  but 
the  cells  are  almost  completely  filled  with  colorless  cell  sap. 

A  longitudinal  section  shows  that  the  epidermal  cells  are  much  elon- 
gated, the  cells  of  the  ground  tissue  less  so,  and  in  both  the  partition  walls 
are  straight.  In  the  fibrous  cells,  both  of  the  fibro- vascular  bundle  and 
those  lying  between,  the  end  walls  are  strongly  oblique.  The  tracheary 
tissue  of  the  xylem  is  made  up  of  small,  spirally-marked  vessels,  and 
larger  ones  with  thickened  rings  or  with  pits  in  the  walls.  The  small, 
spirally- marked  vessels  are  nearest  the  centre,  and  are  the  first  to  be 
formed  in  the  young  bundle. 

The  epidermis  of  the  leaves  is  composed  of  irregular  cells  with  wavy 
outlines  like  those  of  the  ferns.  Breathing  pores,  of  the  same  type  as 
those  in  the  ferns  and  monocotyledons,  are  found  on  both  surfaces,  but 
more  abundant  and  more  perfectly  developed  on  the  lower  surface  of  the 
leaf.  Owing  to  their  small  size  they  are  not  specially  favorable  for  study. 
The  epidermis  is  sparingly  covered  with  unicellular  hairs,  some  of  which 
are  curiously  branched,  being  irregularly  star-shaped.  The  walls  of  these 
cells  are  very  thick,  and  have  little  protuberances  upon  the  outer  surface 
(Fig.  93,  E). 

Cross-sections  of  the  leaf  may  be  made  between  pith  as  already  directed  ; 
or,  by  folding  the  leaf  carefully  several  times,  the  whole  can  be  easily 
sectioned.  The  structure  is  essentially  as  in  the  adder-tongue,  but  the 
epidermal  cells  appear  more  irregular,  and  the  fibro- vascular  bundles  are 


178 


BOTANY. 


better  developed.    They  are  like  those  of  the  stem,  but  somewhat  simpler. 
The  xylem  lies  on  the  upper  side. 

The  ground  tissue  is  composed,  as  in  the  leaves  we  have  studied,  of 
chlorophyll-bearing,  loose  cells,  rather  more  compact  upon  the  upper  side. 
(In  the  majority  of  dicotyledons  the  upper  surface  of  the  leaves  is  nearly  or 


1) 


FIG.  95.  —  A-D,  successive  stages  in  the  development  of  the  flower  of  Capsella, 
x  50.  A,  surface  view.  B-D,  optical  sections,  s,  sepals,  p,  petals,  an. 
stamens,  ay.  pistil.  E,  cross-section  of  the  young  anther,  x  180.  sp.  spore 
mother  cells.  F,  cross-section  of  full-grown  anther,  sp.  pollen  spores,  x  50. 
F',  four  young  pollen  spores,  x  300.  F",  pollen  spores  germinating  upon  the 
stigma,  x  300.  pt.  pollen  tube.  G,  young  pistil  in  optical  section,  x  25.  H, 
cross-section  of  a  somewhat  older  one.  ov.  ovules.  I-L,  development  of  the 
ovule,  sp.  embryo  sac  (macrospore).  I-K,  x  150.  L,  x  50.  M,  embryo  sac 
of  a  full-grown  ovule,  x  150.  Sy.  Synergidse.  o,  egg  cell,  n,  endosperm 
nucleus,  ant.  antipodal  cells.  JV-Q,  development  of  the  embryo,  x  150. 
sus.  suspensor. 

quite  destitute  of  breathing  pores,  and  the  cells  of  the  ground  tissue  below 
the  upper  epidermis  are  closely  packed,  forming  what  is  called  the  "pali- 
sade-parenchyma" of  the  leaf.) 

The  shepherd' s-purse  is  an  admirable  plant  for  the  study  of  the  develop- 
ment of  the  flower  which  is  much  the  same  in  other  angiosperms.  To 
study  this,  it  is  only  necessary  to  teaze  out,  in  a  drop  of  water,  the  tip  of 


DICOTYLEDONS.  179 

a  raceme,  and  putting  on  a  cover  glass,  examine  with  a  power  of  from 
fifty  to  a  hundred  diameters.  In  the  older  stages  it  is  best  to  treat  with 
potash,  which  will  render  the  young  flowers  quite  transparent.  The 
young  flower  (Fig.  95,  A)  is  at  first  a  little  protuberance  composed  of 
perfectly  similar  small  cells  filled  with  dense  protoplasm.  The  first  of  the 
floral  leaves  to  appear  are  the  sepals  which  very  early  arise  as  four  little 
buds  surrounding  the  young  flower  axis  (Fig.  95,  A,  B).  The  stamens 
(<7,  an.}  next  appear,  being  at  first  entirely  similar  to  the  young  sepals. 
The  petals  do  not  appear  until  the  other  parts  of  the  flower  have  reached 
some  size,  and  the  first  tracheary  tissue  appears  in  the  fibro- vascular 
bundle  of  the  flower  stalk  (D).  The  carpels  are  more  or  less  united  from 
the  first,  and  form  at  first  a  sort  of  shallow  cup  with  the  edges  turned  in 
(Z>,  gy.}.  This  cup  rapidly  elongates,  and  the  cavity  enlarges,  becoming 
completely  closed  at  the  top  where  the  short  style  and  stigma  develop. 
The  ovules  arise  in  two  lines  on  the  inner  face  of  each  carpel,  and  the 
tissue  which  bears  them  (placenta)  grows  out  into  the  cavity  of  the  ovary 
until  the  two  placentae  meet  in  the  middle  and  form  a  partition  completely 
across  the  ovary  (Fig.  95,  H). 

The  stamens  soon  show  the  differentiation  into  filament  and  anther, 
but  the  former  remains  very  short  until  immediately  before  the  flowers 
are  ready  to  open.  The  anther  develops  four  sporangia  (pollen  sacs),  the 
process  being  very  similar  to  that  in  such  pteridophytes  as  the  club  mosses. 
Each  sporangium  (Fig.  E,  F]  contains  a  central  mass  of  spore  mother 
cells,  and  a  wall  of  three  layers  of  cells.  The  spore  mother  cells  finally 
separate,  and  the  inner  layer  of  the  wall  cells  becomes  absorbed  much 
as  we  saw  in  the  fern,  and  the  mass  of  mother  cells  thus  floats  free  in  the 
cavity  of  the  sporangium.  Each  one  now  divides  in  precisely  the  same 
way  as  in  the  ferns  and  gymnosperms,  into  four  pollen  spores.  The 
anther  opens  as  described  for  Erythronium. 

By  carefully  picking  to  pieces  the  young  ovaries,  ovules  in  all  stages 
of  development  may  be  found,  and  on  account  of  their  small  size  and 
transparency,  show  beautifully  their  structure.  Being  perfectly  trans- 
parent, it  is  only  necessary  to  mount  them  in  water  and  cover. 

The  young  ovule  (7,  J)  consists  of  a  central,  elongated  body  (nucellus), 
having  a  single  layer  of  cells  enclosing  a  large  central  cell  (the  macrospore 
or  embryo  sac)  (sp.).  The  base  of  the  nucellus  is  surrounded  by  two 
circular  ridges  (i,  n)  of  which  the  inner  is  at  first  higher  than  the  outer 
one,  but  later  (K,  JL),  the  latter  grows  up  above  it  and  completely  conceals 
it  as  well  as  the  nucellus.  One  side  of  the  ovule  grows  much  faster  than 
the  other,  so  that  it  is  completely  bent  upon  itself,  and  the  opening 
between  the  integuments  is  brought  close  to  the  base  of  the  ovule  (Fig. 


180  BOTANY. 

95,  L).  This  opening  is  called  the  "micropyle,"  and  allows  the  pollen 
tube  to  enter. 

The  full-grown  embryo  sac  shows  the  same  structure  as  that  already 
described  in  Monotropa  (page  276),  but  as  the  walls  of  the  full-grown 
ovule  are  thicker  here,  its  structure  is  rather  difficult  to  make  out.  The 
ripe  stigma  is  covered  with  little  papillae  (Fig.  95,  F)  that  hold  the 
pollen  spores  which  may  be  found  here  sending  out  the  pollen  tube.  By 
carefully  opening  the  ovary  and  slightly  crushing  it  in  a  drop  of  water, 
the  pollen  tube  may  sometimes  be  seen  growing  along  the  stalk  of  the 
ovule  until  it  reaches  and  enters  the  micropyle. 

To  study  the  embryo  a  series  of  young  fruits  should  be  selected,  and 
the  ovules  carefully  dissected  out  and  mounted  in  water,  to  which  a  little 
caustic  potash  has  been  added.  The  ovule  will  be  thus  rendered  trans- 
parent, and  by  pressing  gently  on  the  cover  glass  with  a  needle  so  as  to 
flatten  the  ovule  slightly,  there  is  usually  no  trouble  in  seeing  the  embryo 
lying  in  the  upper  part  of  the  embryo  sac,  and  by  pressing  more  firmly 
it  can  often  be  forced  out  upon  the  slide.  The  potash  should  now  be 
removed  as  completely  as  possible  with  blotting  paper,  and  pure  water 
run  under  the  cover  glass. 

The  fertilized  egg  cell  first  secretes  a  membrane,  and  then  divides  into 
a  row  of  cells  (JV)  of  which  the  one  nearest  the  micropyle  is  often  much 
enlarged.  The  cell  at  the  other  end  next  enlarges  and  becomes  divided  by 
walls  at  right  angles  to  each  other  into  eight  cells.  This  globular  mass 
of  cells,  together  with  the  cell  next  to  it,  is  the  embryo  plant,  the  row  of 
cells  to  which  it  is  attached  taking  no  further  part  in  the  process,  and 
being  known  as  the  "suspensor."  Later  the  embryo  becomes  indented 
above  and  forms  two  lobes  ($),  which  are  the  beginnings  of  the  cotyle- 
dons. The  first  root  and  the  stem  arise  from  the  cells  next  the  suspensor. 


CHAPTER   XVIII. 


CLASSIFICATION   OF   DICOTYLEDONS. 

DIVISION  I.  —  Choripetalce. 

NEARLY  all  of  the  dicotyledons  may  be  placed  in  one  of  two 
great  divisions  distinguished  by  the  character  of  the  petals. 
In  the  first  group,  called  Choripetalce,  the  petals  are  separate, 
or  in  some  degenerate  forms  entirely  absent.  As  familiar 
examples  of  this  group,  we  may  select  the  buttercup,  rose, 
pink,  and  many  others. 

The  second  group  (Sympetalce, 
or  Gamopetalce)  comprises  those 
dicotyledons  whose  flowers  have 
the  petals  more  or  less  com- 
pletely united  into  a  tube.  The 
honeysuckles,  mints,  huckle- 
berry, lilac,  etc.,  are  familiar 
representatives  of  the  Sym- 
petalce, which  includes  the  high- 
est of  all  plants. 

The  Choripetalce  may  be  di- 
vided into  six  groups,  including 
twenty-two  orders.  The  first 
group  is  called  luliftorce,  and 
contains  numerous,  familiar 
plants,  mostly  trees.  In  these 
plants,  the  flowers  are  small 
and  inconspicuous,  and  usually 

crowded  into  dense  catkins,  as  in  willows  (Fig.  96)  and 
poplars,  or  in  spikes  or  heads,  as  in  the  lizard-tail  (Fig.  97,  G), 
or  hop  (Fig.  97,  J).  The  individual  flowers  are  very  small 

181 


FIG.  96.—  luliflorsB.  A,  male;  B, 
female  inflorescence  of  a  willow, 
Salix  (Amentacese) ,  x  %.  C,  a 
single  male  flower,  x  2.  D,  a 
female  flower,  x  2.  E,  cross- 
section  of  the  ovary,  x  8.  F,  an 
opening  fruit.  G,  single  seed  with 
its  hairy  appendage,  x  2. 


182 


BOTANY. 


and  simple  in  structure,  being  often  reduced  to  the  gynoecium 
or  andraecium,  carpels  and  stamens  being  almost  always  in 
separate  flowers.  The  outer  leaves  of  the  flower  (sepals  and 
petals)  are  either  entirely  wanting  or  much  reduced,  and  never 
differentiated  into  calyx  and  corolla. 


FIG.  97.  —  Types  of  luliflorse.  A,  branch  of  hazel,  Gorylus  (Cvpuli ferae) ,  x  1. 
c?,male;  ?,  female  inflorescence.  B,  a  single  male  flower,  x  3.  C,  section 
of  the  ovary  of  a  female  flower,  x  25.  D,  acorn  of  red  oak,  Quercus 
(Cupuliferse),  x  %.  E,  seed  of  white  birch,  Betula  (Betulacesd) ,  x  3.  F, 
fruit  of  horn-bean,  Garpinus  (Cupuliferse) ,  x  l.  G,  lizard-tail,  tiaururus 
(Saururese),  x  V4.  H,  a  single  flower,  x  2.  I,  female  inflorescence  of  the  hop, 
Humulus  (Cannabinese),  x~  1.  J,  a  single  scale  with  two  flowers,  x  1.  X, 
a  male  flower  of  a  nettle,  Urtica  (Urticacese) ,  x  5. 

In  the  willows  (Fig.  96)  the  stamens  are  bright-colored,  so 
that  the  flowers  are  quite  showy,  and  attract  numerous  insects 
which  visit  them  for  pollen  and  nectar,  and  serve  to  carry  the 
pollen  to  the  pistillate  flowers,  thus  insuring  their  fertilization. 
In  the  majority  of  the  group,  however,  the  flowers  are  wind- 
fertilized.  An  excellent  example  of  this  is  seen  in  the  common 
hazel  (Fig.  97,  A).  The  male  flowers  are  produced  in  great 


CLASSIFICATION   OF  DICOTYLEDONS.  183 

numbers  in  drooping  catkins  at  the  ends  of  the  branches, 
shedding  the  pollen  in  early  spring  before  the  leaves  unfold. 
The  female  flowers  are  produced  on  the  same  branches,  but 
lower  down,  and  in  much  smaller  numbers.  The  stigmas  are 
long,  and  covered  with  minute  hairs  that  catch  the  pollen  which 
is  shaken  out  in  clouds  every  time  the  plant  is  shaken  by  the 
wind,  and  falls  in  a  shower  over  the  stigmas.  A  similar 
arrangement  is  seen  in  the  oaks,  hickories,  and  walnuts. 

There  are  three  orders  of  the  luliflorce :  Amentacece,  Piperi- 
nece,  and  Urticinee.  The  first  contains  the  birches  (Betulacece) ; 
oaks,  beeches,  hazels,  etc.  (CupuUferce)  ;  walnuts  and  hickories 
(Juglandem)  ;  willows  and  poplars  (Salicacece).  They  are  all 
trees  or  shrubs ;  the  fruit  is  often  a  nut,  and  the  embryo  is 
very  large,  completely  filling  it. 

The  Piperinece  are  mostly  tropical  plants,  and  include  the 
pepper  plant  (Piper),  as  well  as  other  plants  with  similar 
properties.  Of  our  native  forms,  the  only  common  one  is  the 
lizard-tail  (Saururus),  not  uncommon  in  swampy  ground.  In 
these  plants,  the  calyx  and  corolla  are  entirely  absent,  but  the 
flowers  have  both  carpels  and  stamens  (Fig.  97,  H). 

The  Urticince  include,  among  our  common  plants,  the  nettle 
family  (TJrticacece)  ;  plane  family  (Platanece) ,  represented  by 
the  sycamore  or  buttonwood  (Platanus)  ;  the  hemp  family 
(Cannabinece)  ;  and  the  elm  family  (Ulmacece).  The  flowers 
usually  have  a  calyx,  and  may  have  only  stamens  or  carpels, 
or  both.  Sometimes  the  part  of  the  stem  bearing  the  flowers 
may  become  enlarged  and  juicy,  forming  a  fruit-like  structure. 
Well-known  examples  of  this  are  the  fig  and  mulberry. 

The  second  group  of  the  Choripetalce  is  called  Centrospermte, 
and  includes  but  a  single  order  comprising  seven  families,  all 
of  which,  except  one  (Nyctaginece) ,  are  represented  by  numer- 
ous native  species.  The  latter  comprises  mostly  tropical  plants, 
and  is  represented  in  our  gardens  by  the  showy  "four-o'clock7' 
(Mirabilis').  In  this  plant,  as  in  most  of  the  order,  the  corolla 
is  absent,  but  here  the  calyx  is  large  and  brightly  colored, 


184 


BOTANY. 


resembling  closely  the  corolla  of  a  morning-glory  or  petunia. 
The  stamens  are  usually  more  numerous  than  the  sepals,  and 
the  pistil,  though  composed  of  several  carpels,  has,  as  a  rule, 
but  a  single  cavity  with  the  ovules  arising  from  the  base, 
though  sometimes  the  ovary  is  several  celled. 


FIG.  98. — Types  of  Centrospermse.  A,  plant  of  spring-beauty,  Claytonia 
(Portulacacese) ,  x  %•  B,  a  single  flower,  x  1.  C,  fruit,  with  the  sepals  re- 
moved, x  2.  D,  section  of  the  seed,  showing  the  curved  embryo  (em.),  x  5. 
E,  single  flower  of  smart-weed,  Polygonvm  (Polygonacese),  x  2.  F,  the 
pistil,  x  2.  G,  section  of  the  ovary,  showing  the  single  ovule,  x  4.  H,  sec- 
tion of  the  seed,  x  2.  /,  base  of  the  leaf,  showing  the  sheath,  x  1.  J,  flower 
of  pig-weed,  Chenopodinm  (Chenopodiacese) ,  x  3 :  i,  from  without;  n,  in 
section.  K,  flower  of  the  poke-weed,  Phytolacca  (Phytolaccacese) ,  x  2.  L, 
fire-pink,  Silene  (Caryophyllacese) ,  x  %.  M,  a  flower  with  half  of  the  calyx 
and  corolla  removed,  x  1.  JV,  ripe  fruit  of  mouse-ear  chickweed,  Cerastium 
(Caryophyllacese) ,  opening  by  ten  teeth  at  the  summit,  x  2.  0,  diagram  of 
the  flower  of  Silene. 

The  first  family  (Polygonece)  is  represented  by  the  various 
species  of  *Polygonum  (knotgrass,  smart-weed,  etc.),  and  among 
cultivated  plants  by  the  buckwheat  (Fagopyrum).  The  goose- 
foot  or  pig-weed  (Chenopodium)  among  native  plants,  and  the 
beet  and  spinach  of  the  gardens  are  examples  of  the  family 


CLASSIFICATION   OF  DICOTYLEDONS.  185 

Chenopodiacem.  Nearly  resembling  the  last  is  the  amaranth 
family  (Amarantacece) ,  of  which  the  showy  amaranths  arid 
coxcombs  of  the  gardens,  and  the  coarse,  green  amaranth  or 
pig-weed  are  representatives. 

The  poke-weed  (Phytolacca)  (Fig.  98,  K),  so  conspicuous  in 
autumn  on  account  of  its  dark-purple  clusters  of  berries  and 
crimson  stalks,  is  our  only  representative  of  the  family  Pliyto- 
laccacece.  The  two  highest  families  are  the  purslane  family 
(Portulacacece)  and  pink  family  (Caryophyllece) .  These  are 
mostly  plants  with  showy  flowers  in  which  the  petals  are 
large  and  conspicuous,  though  some  of  the  pink  family,  e.g. 
some  chick-weeds,  have  no  petals.  Of  the  purslane  family 
the  portulacas  of  the  gardens,  and  the  common  purslane  or 
"pusley,"  and  the  spring-beauty  (Claytonia)  (Fig.  98,  A)  are 
the  commonest  examples.  The  pink  family  is  represented 
by  many  common  and  often  showy  plants.  The  carnation, 
Japanese  pinks,  and  sweet-william,  all  belonging  to  the  genus 
Diantlms,  of  which  there  are  also  two  or  three  native  species, 
are  among  the  showiest  of  the  family.  The  genera  Lychnis 
and  Silene  (Fig.  98,  L)  also  contain  very  showy  species.  Of 
the  less  conspicuous  genera,  the  chick-weeds  (Cerastium  and 
SteUaria)  are  the  most  familiar. 

The  third  group  of  the  Choripetalce  (tjie  Aphanocydce)  is  a 
very  large  one  and  includes  many  common  plants  distributed 
among  five  orders.  The  lower  ones  have  all  the  parts  of  the 
flower  entirely  separate,  and  often  indefinite  in  number;  the 
higher  have  the  gynoecium  composed  of  two  or  more  carpels 
united  to  form  a  compound  pistil. 

The  first  order  (Polycarpce)  includes  ten  families,  of  which 
the  buttercup  family  (Rannuculacece)  is  the  most  familiar. 
The  plants  of  this  family  show  much  variation  in  the  details 
of  the  flowers,  which  are  usually  showy,  but  the  general  plan 
is  much  the  same.  In  some  of  them,  like  the  anemones  (Fig. 
99,  A),  clematis,  and  others,  the  corolla  is  absent,  but  the 
sepals  are  large  and  brightly  colored  so  as  to  appear  like  petals. 


186 


BOTANY. 


In  the  columbine  (Aquilegia)  (Fig.  99,  F)  the  petals  are 
tubular,  forming  nectaries,  and  in  the  larkspur  (Fig.  99,  T) 
one  of  the  sepals  is  similarly  changed. 

Representing  the  custard-apple  family   (Anonacece)  is  the 
curious  papaw  (Asimina),  common  in  many  parts  of  the  United 


FIG.  99.  — Types  of  Aphanocyclse  (Polycarpse) ,  family  Ranunculacese.  A,  Rue 
anemone  (Anemonilld) ,  x  %.  B,  a  fruit,  x  2.  C,  section  of  the  same.  D, 
section  of  a  buttercup  flower  (Ranunculus),  x  1%.  E,  diagram  of  buttercup 
flower.  F,  wild  columbine  (Aquilegia),  x  %.  G,  one  of  the  spur-shaped 
petals,  x  1.  ff,  the  five  pistils,  x  l.  jr  longitudinal  section  of  the  fruit,  x  1. 
J,  flower  of  larkspur  (Delphinium),  x  \.  K,  the  four  petals  and  stamens, 
after  the  removal  of  the  five  colored  and  petal-like  sepals,  x  1. 

States  (Fig.  100,  A).     The  family  is  mainly  a  tropical  one, 
but  this  species  extends  as  far  north  as  southern  Michigan. 

The  magnolia  family  (Magnoliacece)  has  several  common 
members,  the  most  widely  distributed  being,  perhaps,  the 
tulip-tree  (Liriodendron)  (Fig.  100,  C),  much  valued  for  its 
timber.  Besides  this  there  are  several  species  of  magnolia, 
the  most  northerly  species  being  the  sweet-bay  (Magnolia 


CLASSIFICATION  OF  DICOTYLEDONS. 


187 


glauca)  of  the  Atlantic  States,  and  the  cucumber-tree  (M. 
acuminata) ;  the  great  magnolia  (M.  grandijlora)  is  not  hardy 
in  the  northern  states. 

The  sweet-scented  shrub  (Calycanthus)  (Fig.  100,  G)  is  the 
only  member  of  the  family  Calycanthacece  found  within  our 


FIG.  100.  —  Types  of  Aphanocyclse  (Polycarpse) .  A,  branch  of  papaw,  Asimina 
(Anonacess),  x  %.  B,  section  of  the  flower,  x  1.  C,  flower  and  leaf  of  tulip- 
tree,  Liriodendron  (Magnoliacese) ,  x  %.  Z>,  section  of  a  flower,  x  %.  E,  a 
ripe  fruit,  x  l.  F,  diagram  of  the  flower.  G,  flower  of  the  sweet-scented 
shrub,  Calycanthus  (Calycanthacese),  x% 

limits.     It  grows  wild  in  the  southern  states,  and  is  cultivated 
for  its  sweet-scented,  dull,  reddish  flowers. 

The  barberry  (Herberts)  (Fig.  101,  A)  is  the  type  of  the 
family  Berberidece,  which  also  includes  the  curious  mandrake 
or  may-apple  (Podophyllum)  (Fig.  101,  D),  and  the  twin-leaf 
or  rheumatism-root  (Jejfersonia) ,  whose  curious  seed  vessel  is 
shown  in  Figure  101,  G.  The  fruit  of  the  barberry  and  may- 
apple  are  edible,  but  the  root  of  the  latter  is  poisonous. 


188 


BOTANY. 


The  curious  woody  twiner,  moon-seed  (Menispermum)  (Fig. 
101,  /),  is  the  sole  example  in  the  northern  states  of  the  family 
Menispermece  to  which  it  belongs.  The  flowers  are  dioecious, 
and  the  pistillate  flowers  are  succeeded  by  black  fruits  looking 
like  grapes.  The  flattened,  bony  seed  is  curiously  sculptured, 
and  has  the  embryo  curled  up  within  it. 

A 


em.> 


FIG.  101.  — Types  of  Aphanocyclse  (Polycarpse) .  A-H,  Berberidacese.  A, 
flower  of  barberry  (Berberis),  x  2.  B,  the  same  in  section.  6',  a  stamen, 
showing  the  method  of  opening,  x  3.  /),  flower  of  may-apple  (Podophyllum) , 
x  %.  E,  section  of  the  ovary  of  D,  x  1.  f\  diagram  of  the  flower.  G,  ripe 
fruit  of  twin-leaf  (Jefl'ersonia) ,  opening  by  a  lid,  x  l/2.  H,  section  of  seed, 
showing  the  embryo  (em.),  x  2.  /,  young  leaf  and  cluster  of  male  flowers  of 
moon-seed,  Menispermum  (Menispermete) ,  x  1.  J,  a  single  male  flower, 
x  2.  K,  section  of  a  female  flower,  x  2.  L,  ripe  seed,  x  l.  M,  section  of  M, 
showing  the  curved  embryo. 

The  last  two  families  of  the  order,  the  laurel  family  (Lauri- 
nece)  and  the  nutmeg  family  (Myristicinece)  are  mostly  tropical 
plants,  characterized  by  the  fragrance  of  the  bark,  leaves,  and 
fruit.  The  former  is  represented  by  the  sassafras  and  spice- 
bush,  common  throughout  the  eastern  United  States.  The 
latter  has  no  members  within  our  borders,  but  is  familiar  to 
all  through  the  common  nutmeg,  which  is  the  seed  of  Myristica 


CLASSIFICATION   OF  DICOTYLEDONS. 


189 


fragrans  of  the  East  Indies.     "  Mace  "  is  the  "  aril "  or  cover- 
ing of  the  seed  of  the  same  plant. 

The  second  order  of  the  Aphanocydce  comprises  a  number  of 
aquatic  plants,  mostly  of  large  size,  and  is  known  as  the 
Hydropeltidince.  The  flowers  and  leaves  are  usually  very 


FIG.  102.  —  Types  of  Aphanocyclse  (Hydropeltidinss) .  A,  yellow  water-lily, 
Nymphsea  (Nymphssacess) ,  x  %.  B,  a  leaf  of  the  same,  x  3/6.  C,  freshly 
opened  flower,  with  the  large  petal-like  sepals  removed,  x  %.  p,  petals,  an. 
stamens,  si.  stigma.  Z),  section  of  the  ovary,  x  2.  E,  young  fruit,  x  y2. 
F,  lotus,  Nelumbo  (Nelumbiese) .  x  V«.  G,  a  stamen,  x  1.  H,  the  large 
receptacle,  with  the  separate  pistils  sunk  in  its  surface,  x  %.  1,  section  of  a 
single  pistil,  x  2.  ov.  the  ovule.  J,  upper  part  of  a  section  through  the 
stigma  and  ovule  (ov.),  x  4. 

large,  the  latter  usually  nearly  round  in  outline,  and  fre- 
quently with  the  stalk  inserted  near  the  middle.  The  leaves 
of  the  perigone  are  numerous,  and  sometimes  merge  gradually 
into  the  stamens,  as  we  find  in  the  common  white  water-lily 
(Castalia). 


190  BOTANY. 

There  are  three  families,  all  represented  within  the  United' 
States.  The  first  (Nelumbiece)  has  but  a  single  species,  the 
yellow  lotus  or  nelumbo  (Nelumbo  lutea),  common  in  the 
waters  of  the  west  and  southwest,  but  rare  eastward  (Fig.  101, 
F) .  In  this  flower,  the  end  of  the  flower  axis  is  much  enlarged, 
looking  like  the  rose  of  a  watering-pot,  and  has  the  large, 
separate  carpels  embedded  in  its  upper  surface.  When  ripe, 
each  forms  a  nut-like  fruit  which  is  edible.  There  are  but 
two  species  of  Nelumbo  known,  the  second  one  (JV.  spedosa) 
being  a  native  of  southeastern  Asia,  and  probably  found  in 
ancient  times  in  Egypt,  as  it  is  represented  frequently  in  the 
pictures  and  carvings  of  the  ancient  Egyptians.  It  differs 
mainly  from  our  species  in  the  color  of  its  flowers  which  are 
red  instead  of  yellow.  It  has  recently  been  introduced  into 
New  Jersey  where  it  has  become  well  established  in  several 
localities. 

The  second  family  (Cabombece)  is  also  represented  at  the 
north  by  but  one  species,  the  water  shield  (Brasenia),  not 
uncommon  in  marshes.  Its  flowers  are  quite  small,  of  a  dull- 
purple  color,  and  the  leaves  oval  in  outline  and  centrally 
peltate,  i.e.  the  leaf  stalk  inserted  in  the  centre.  The  whole 
plant  is  covered  with  a  transparent  gelatinous  coat. 

The  third  family  (Nymphceacece)  includes  the  common  white 
water-lilies  (Castalia)  and  the  yellow  water-lilies  (Nymphcea) 
(Fig.  102,  A).  In  the  latter  the  petals  are  small  and  incon- 
spicuous (Fig.  102,  C,p),  but  the  sepals  are  large  and  showy. 
In  this  family  the  carpels,  instead  of  being  separate,  are 
united  into  a  large  compound  pistil.  The  water-lilies  reach 
their  greatest  perfection  in  the  tropics,  where  they  attain  an 
enormous  size,  the  white,  blue,  or  red  flowers  of  some  species 
being  thirty  centimetres  or  more  in  diameter,  and  the  leaves 
of  the  great  Victoria  regia  of  the  Amazon  reaching  two  metres 
or  more  in  width. 

The  third  order  of  the  Aphanocydce  (Rhceadince  or  Oruci- 
florce)  comprises  a  number  of  common  plants,  principally 


CLASSIFICATION   OF  DICOTYLEDONS. 


191 


characterized  by  having  the  parts  of  the  flowers  in  twos  or 
fours,  so  that  they  are  more  or  less  distinctly  cross-shaped, 
whence  the  name  Cruciftorce. 

There  are  four  families,  of  which  the  first  is  the  poppy 
family  (Papaveracece) ,  including  the  poppies,  eschscholtzias, 
Mexican  or  prickly  poppy  (Argemone),  etc.,  of  the  gardens, 

O- 


FIG.  103.  — Types  of  Aphanocyclse  (Rhwadinse) .  A,  plant  of  blood-root, 
Sanyuinaria  (Papaveracese) ,  x  y3.  B,  a  single  flower,  x  l.  C,  fruit,  x  %. 
D,  section  of  the  seed.  em.  embryo,  x  2.  E,  diagram  of  the  flower.  F, 
flower  of  Dutchman's  breeches,  Dicentra  (Fumariacese) ,  x  1.  G,  group  of 
three  stamens  of  the  same,  x  2.  H,  one  of  the  inner  petals,  x  2.  /,  fruit  of 
celandine  poppy,  Stylophorum  (Papaveracese) ,  x  %.  J,  flower  of  mustard, 
Brassica  (Cruciferze) ,  x  1.  K,  the  same,  with  the  petals  removed,  x  2. 
L,  fruit  of  the  same,  x  1. 

and  the  blood-root  (Sanguinaria),  celandine  poppy  (Stylo- 
phorum),  and  a  few  other  wild  plants  (see  Fig.  103,  A-I). 
Most  of  the  family  have  a  colored  juice  (latex),  which  is  white 
in  the  poppy,  yellow  in  celandine  and  Argemone,  and  orange- 
red  in  the  blood-root.  From  the  latex  of  the  opium  poppy  the 
opium  of  commerce  is  extracted. 


192  BOTANY. 

The  second  family,  the  fumitories  (Fumariacece)  are  delicate, 
smooth  plants,  with  curious  flowers  and  compound  leaves.  The 
garden  bleeding-heart  (Dicentra  spectabilis)  and  the  pretty,  wild 
Dicentras  (Fig.  103,  F)  are  familiar  to  nearly  every  one. 

Other  examples  are  the  mountain  fringe  (Adlumia),  a  climb- 
ing species,  and  several  species  of  Corydalis,  differing  mainly 
from  Dicentra  in  having  the  corolla  one-sided. 

The  mustard  family  (Cruciferce)  comprises  by  far  the  greater 
part  of  the  order.  The  shepherd's-purse,  already  studied, 
belongs  here,  and  may  be  taken  as  a  type  of  the  family.  There 
is  great  uniformity  in  all  as  regards  the  flowers,  so  that  the 
classification  is  based  mainly  on  differences  in  the  fruit  and 
seeds.  Many  of  the  most  valuable  garden  vegetables,  as  well 
as  a  few  more  or  less  valuable  wild  plants,  are  members  of  the 
family,  which,  however,  includes  some  troublesome  weeds. 
Cabbages,  turnips,  radishes,  with  all  their  varieties,  belong 
here,  as  well  as  numerous  species  of  wild  cresses.  A  few  like 
the  wall-flower  (Cheiranthus)  and  stock  (Mattliiola)  are  culti- 
vated for  ornament. 

The  last  family  is  the  caper  family  (Capparidece) ,  repre- 
sented by  only  a  few  not  common  plants.  The  type  of  the 
order  is  Capparis,  whose  pickled  flower-buds  constitute  capers. 

The  fourth  order  (Cistiflorce)  of  the  Aphanocyclce  is  a  very 
large  one,  but  the  majority  of  the  sixteen  families  included  in 
it  are  not  represented  within  our  limits.  The  flowers  have 
the  sepals  and  petals  in  fives,  the  stamens  either  the  same  or 
more  numerous. 

Among  the  commoner  members  of  the  order  are  the  migno- 
nettes (Resedacece)  and  the  violets  (Violacece),  of  which  the 
various  wild  and  cultivated  species  are  familiar  plants  (Fig. 
104,  A,  M).  The  sundews  (Droseracece)  are  most  extraor- 
dinary plants,  growing  in  boggy  land  over  pretty  much  he 
whole  world.  They  are  represented  in  the  United  States  by 
several  species  of  sundew  (Drosera),  and  the  still  more  curious 
Venus's-flytrap  (Dioncea)  of  North  Carolina.  The  leaves  of 


CLASSIFICATION   OF  DICOTYLEDONS. 


193 


the  latter  are  sensitive,  and  composed  of  two  parts  which  snap 
together  like  a  steel  trap.  If  an  insect  lights  upon  the  leaf, 
and  touches  certain  hairs  upon  its  upper  surface,  the  two  parts 
snap  together,  holding  the  insect  tightly.  A  digestive  fluid  is 
secreted  by  glands  upon  the  inner  surface  of  the  leaf,  and  in  a 
short  time  the  captured  insect  is  actually  digested  and  absorbed 


FIG.  104.  —  Types  of  Aphanocyclse  (Cistiflorse).  A,  flower  of  wild  blue  violet, 
Viola  (Violacese.) ,  x  1.  B,  the  lower  petal  prolonged  behind  into  a  sac  or 
spur,  x  1.  C,  the  stamens,  x  2.  1),  pistil,  x  2.  E,  a  leaf,  x  %.  F,  section 
of  the  ovary,  x  2.  G,  the  fruit,  x  l.  H,  the  same  after  it  has  opened,  x"l. 
J,  diagram  of  the  flower.  J,  flower  of  mignonette,  Resc.da  (Resedacese) ,  x  2. 
K,  a  petal,  x  3.  L,  cross-section  of  the  ovary,  x  3.  M,  fruit,  x  1.  N,  plant 
of  sundew,  Drosera  (Droseracese),  x  y2.  0,  a  leaf  that  has  captured  a  mos- 
quito, x  2.  P,  flower  of  another  species  (D.  filiformis),  x  2.  Q,  cross- 
section  of  the  ovary,  x  4. 

by  the  leaves.  The  same  process  takes  place  in  the  sundew 
(Fig.  104,  N)  where,  however,  the  mechanism  is  somewhat 
different.  Here  the  tentacles,  with  which  the  leaf  is  studded, 
secrete  a  sticky  fluid  which  holds  any  small  insect  that  may 
light  upon  it.  The  tentacles  now  slowly  bend  inward  and 
finally  the  edges  of  the  leaf  as  well,  until  the  captured  insect 


194 


BOTANY. 


is  firmly  held,  when  a  digestive  process,  similar  to  that  in 
Dioncea,  takes  place.  This  curious  habit  is  probably  to  be 
explained  from  the  position  where  the  plant  grows,  the  roots 
being  in  water  where  there  does  not  seem  to  be  a  sufficient 
supply  of  nitrogenous  matter  for  the  wants  of  the  plant,  which 
supplements  the  supply  from  the  bodies  of  the  captured  insects. 
Similar  in  their  habits,  but  differing  much  in  appearance 
from  the  sundews,  are  the  pitcher-plants  (Sarraceniacece),  of 
which  one  species  (Sarracenia  purpurea)  is  very  common  in 

B 


FIG.  105.  —  Types  of  Aphanocyclse  (Cistiftorse) .  A,  B,  leaves  of  the  pitcher- 
plant,  Sarracenia  (Sarraceniacese,) .  A,  from  the  side;  B,  from  in  front,  x  %. 
C,  St.  John's-wort  (Hypericum),  x  y2.  /),  a  flower,  x  1.  E,  the  pistil,  x  2. 

•Or,  cross-section  of  the  ovary,  x  4.    H,  diagram  of  the  flower. 

peat  bogs  throughout  the  northern  United  States.  In  this 
species  (Fig.  105,  A,  -B),  the  leaves  form  a  rosette,  from  the 
centre  of  which  arises  in  early  summer  a  tall  stalk  bearing  a 
single,  large,  nodding,  dark-reddish  flower  with  a  curious 
umbrella-shaped  pistil.  The  leaf  stalk  is  hollow  and  swollen, 
with  a  broad  wing  on  one  side,  and  the  blade  of  the  leaf 
forms  a  sort  of  hood  at  the  top.  The  interior  of  the  pitcher  is 
covered  above  with  stiff,  downward-pointing  hairs,  while  below 
it  is  very  smooth.  Insects  readily  enter  the  pitcher,  but  on 


CLASSIFICATION   OF  DICOTYLEDONS.  195 

attempting  to  get  out,  the  smooth,  slippery  wall  at  the  bottom, 
and  the  stiff,  downward-directed  hairs  above,  prevent  their 
escape,  and  they  fall  into  the  fluid  which  fills  the  bottom  of 
the  cup  and  are  drowned,  the  leaf  absorbing  the  nitrogenous 
compounds  given  off  during  the  process  of  decomposition. 
There  are  other  species  common  in  the  southern  states,  and  a 
California  pitcher-plant  (Darlingtonia)  has  a  colored  appendage 
at  the  mouth  of  the  pitcher  which  serves  to  lure  insects  into 
the  trap. 

Another  family  of  pitcher-plants  (Nepenthece)  is  found  in 
the  warmer  parts  of  the  old  world,  and  some  of  them  are 
occasionally  cultivated  in  greenhouses.  In  these  the  pitchers 
are  borne  at  the  tips  of  the  leaves  attached  to  a  long  tendril. 

Two  other  families  of  the  order  contain  familiar  native 
plants,  the  rock-rose  family  (Cistacece),  and  the  St.  John's- 
worts  (Hypericacece) .  The  latter  particularly  are  common 
plants,  with  numerous  showy  yellow  flowers,  the  petals  usually 
marked  with  black  specks,  and  the  leaves  having  clear  dots 
scattered  through  them.  The  stamens  are  numerous,  and  often 
in  several  distinct  groups  (Fig.  105,  (7,  D). 

The  last  order  of  the  Aphanocydce  (the  Columniferce)  has 
three  families,  of  which  two,  the  mallows  (Malvacece),  and  the 
lindens  (Tiliacece),  include  well-known  species.  Of  the  former, 
the  various  species  of  mallows  (Fig.  106,  A)  belonging  to  the 
genus  Malva  are  common,  as  well  as  some  species  of  Hibiscus, 
including  the  showy  swamp  Hibiscus  or  rose-mallow  (H.  mos- 
cheutos),  common  in  salt  marshes  and  in  the  fresh-water 
marshes  of  the  great  lake  region.  The  hollyhock  and  shrubby 
Althcea  are  familiar  cultivated  plants  of  this  order,  and  the 
cotton-plant  (Gfossypium)  also  belongs  here.  In  all  of  these 
the  stamens  are  much  branched,  and  united  into  a  tube  enclos- 
ing the  style.  Most  of  them  are  characterized  also  by  the 
development  of  great  quantities  of  a  mucilaginous  matter 
within  their  tissues. 

The  common  basswood  ( Tilia)  is  the  commonest  representa- 


196 


BOTANY. 


tive  of  the  family  Tiliacece  -(Fig.  106,  G).  The  nearly  related 
European  linden,  or  lime-tree,  is  sometimes  planted.  Its  leaves 
are  ordinarily  somewhat  smaller  than  our  native  species,  which 
it,  however,  closely  resembles. 

The  fourth  group  of  the  Choripetalce  is  the  Eucyclce.     The 
flowers  most  commonly  have  the  parts  in  fives,  and  the  stamens 


cm. 


FIG.  106.  —  Types  of  Aphanocyclse  (ColumnifersR) .  A,  flower  and  leaf  of  the 
common  mallow,  Malva  (Malyacess),  x  %.  B,  a  flower  bud,  x  1.  C,  section 
of  a  flower,  x  2.  D,  the  fruit,  x  2.  E,  section  of  one  division  of  the  fruit, 
with  the  enclosed  seed,  x  3.  em.  the  embryo.  F,  diagram  of  the  flower.  G, 
leaf  and  inflorescence  of  the  basswood,  Tilia  (Tiliacese),  x  y3.  br.  a  bract. 
H,  a  single  flower,  x  1.  7,  group  of  stamens,  with  petal-like  appendage  (x), 
x  2.  J,  diagram  of  the  flower. 

are  never  more  than  twice  as  many  as  the  sepals.  The  carpels 
are  usually  more  or  less  completely  united  into  a  compound 
pistil.  There  are  four  orders,  comprising  twenty-five  families. 
The  first  order  (Gruinales)  includes  six  families,  consisting 
for  the  most  part  of  plants  with  conspicuous  flowers.  Here 
belong  the  geraniums  (Fig.  107,  A),  represented  by  the  wild 
geraniums  and  crane's-bill,  and  the  very  showy  geraniums 


CLASSIFICATION   OF  DICOTYLEDONS. 


197 


(Pelargonium)  of  the  gardens.  The  nasturtiums  (  Tropceolum) 
represent  another  family,  mostly  tropical,  and  the  wood-sorrels 
(Oxalis)  (Fig.  107,  J)  are  common,  both  wild  and  cultivated. 
The  most  useful  member  of  the  order  is  unquestionably  the 
common  flax  (Linum),  of  which  there  are  also  several  native 


FIG.  107.  — Types  of  Eucyclse  (Gruinales).  A,  wild  crane's-bill  Geranium 
(Geraniacese) ,  x  %.  B,  a  petal,  x  1.  C,  the  young  fruit,  the  styles  united  in  a 
column,  x  %.  I),  the  ripe  fruit,  the  styles  separating  to  discharge  the  seeds, 
x  %.  E,  section  of  a  seed,  x  2.  F,  wild  flax.  Linum  (Linacese),  x  %.  G, 
a  single  flower,  x  2.  H,  cross-section  of  the  young  fruit,  x  3.  I,  flower.  J, 
leaf  of  wood-sorrel,  Oxalis  (Oxalidese),  x  l.  K,  the  stamens  and  pistil,  x  2. 
L,  flower  of  jewel-weed,  Impatiens  (Balsaminese),  x  1.  M,  the  same,  with 
the  parts  separated,  p,  petals,  s,  sepals,  an.  stamens,  yy.  pistil.  N,  fruit, 
x  1.  O,  the  same,  opening.  P,  a  seed,  x  2. 

species  (Fig.  107,  F).  These  are  types  of  the  flax  family 
(Linacece).  Linen  is  the  product  of  the  tough,  fibrous  inner 
bark  of  L.  usitatissimum,  which  has  been  cultivated  for  its 
fibre  from  time  immemorial.  The  last  family  is  the  balsam 
family  (Balsaminece).  The  jewel-weed  or  touch-me-not  (Impa- 
tius),  so  called  from  the  sensitive  pods  which  spring  open  on 


198 


BOTANY. 


being  touched,  is  very  common  in  moist  ground  everywhere 
(Fig.  107,  L-P).  The  garden  balsam,  or  lady's  slipper,  is  a 
related  species  (J.  balsamina). 

The  second  order  ( Terebinthince)  contains  but  few  common 
plants.  There  are  six  families,  mostly  inhabitants  of  the 
warmer  parts  of  the  world.  The  best-known  members  of  the 


Fio.  108. — EucyclsB  (Terebinthinse,  ^Esculinse).  A,  leaves  and  flowers  of 
sugar-maple,  Acer  (Aceracese) ,  x  %  S,  a  male  flower,  x  2.  C,  diagram  of  a 
perfect  flower.  D,  fruit  of  the  silver-maple,  x  %.  E,  section  across  the 
seed,  x  2.  F,  embryo  removed  from  the  seed,  x  1.  G,  leaves  and  flowers  of 
bladder-nut,  Staphylea  (Sapindacese) ,  x  %.  H,  section  of  a  flower,  x  2.  /, 
diagram  of  the  flower.  J,  flower  of  buckeye  (sEscidus),  x  1%.  K,  flower 
of  smoke-tree,  Rhus  (Anacardiacese) ,  x  3.  //,  the  same,  in  section. 

order  are  the  orange,  lemon,  citron,  and  their  allies.  Of  our 
native  plants  the  prickly  ash  (Zanthoxylum),  and  the  various 
species  of  sumach  (Rhus),  are  the  best  known.  In  the  latter 
genus  belong  the  poison  ivy  (R.  toxicodendron)  and  the  poison 
dogwood  (R.  venenata).  The  Venetian  sumach  or  smoke-tree 
(R.  Cotinus)  is  commonly  planted  for  ornament. 


CLASSIFICATION   OF  DICOTYLEDONS.  199 

The  third  order  of  the  Eucydce,  the  ^Esculince,  embraces 
six  families,  of  which  three,  the  horsechestnuts,  etc.  (Sapin- 
dacece),ihe  maples  (Aceracece),  and  the  milkworts  (Polygalacece), 
have  several  representatives  in  the  northern  United  States. 
Of  the  first  the  buckeye  (^Esculus)  (Fig.  108,  J)  and  the 
bladder-nut  (Staphylea)  (Fig.  108,  G)  are  the  commonest 
native  genera,  while  the  horsechestnut  (^Esculus  hippocas- 
tanum)  is  everywhere  planted. 

The  various  species  of  maple  (Acer)  are  familiar  examples 
of  the  Aceracece  (see  Fig.  106,  A,  F). 

The  fourth  and  last  order  of  the  Eucydce,  the  Frangulince, 
is  composed  mainly  of  plants  with  inconspicuous  flowers,  the 
stamens  as  many  as  the. petals.  Not  infrequently  they  are 
dioecious,  or  in  some,  like  the  grape,  some  of  the  flowers  may 
be  unisexual  while  others  are  hermaphrodite  (i.e.  have  both 
stamens  and  pistil).  Among  the  commoner  plants  of  the 
order  may  be  mentioned  the  spindle-tree,  or  burning-bush,  as 
it  is  sometimes  called  (Euonymus)  (Fig.  109,  A),  and  the 
climbing  bitter-sweet  (Celastrus)  (Fig.  109,  D),  belonging  to 
the  family  Celastracece ;  the  holly  and  black  alder,  species 
of  Ilex,  are  examples  of  the  family  Aquifoliacece  ;  the  various 
species  of  grape  (Vitis),  the  Virginia  creeper  (Ampelopsis 
quinquefolia) ,  and  one  or  two  other  cultivated  species  of  the 
latter,  represent  the  vine  family  (Vitacece  or  Ampelidce),  and 
the  buckthorn  (Rhamnus)  is  the  type  of  the  Rhamnacece. 

The  fifth  group  of  the  Choripetalce,  is  a  small  one,  comprising 
but  a  single  order  (Tricoccce).  The  flowers  are  small  and 
inconspicuous,  though  sometimes,  as  in  some  Euphorbias  and 
the  showy  Poinsettia  of  the  greenhouses,  the  leaves  or  bracts 
surrounding  the  inflorescence  are  conspicuously  colored,  giving 
the  whole  the  appearance  of  a  large,  showy,  single  flower.  In 
northern  countries  the  plants  are  mostly  small  weeds,  of  which 
the  various  spurges  or  Euphorbias  are  the  most  familiar. 
These  plants  (Fig.  109,  K)  have  the  small  flowers  surrounded 
by  a  cup-shaped  involucre  (L,  M )  so  that  the  whole  inflores- 


200 


BOTANY. 


cence  looks  like  a  single  flower.  In.  the  spurges,  as  in  the 
other  members  of  the  order,  the  flowers  are  very  simple,  being 
often  reduced  to  a  single  stamen  or  pistil  (Fig.  109,  M,  N). 
The  plants  generally  abound  in  a  milky  juice  which  is  often 


Fio.  109.  —  Eucylae  (Frangulinse) ,  Tricoccss.  A,  flowers  of  spindle-tree, 
Euonymus,  (Celastracese) ,  x  l.  B,  cross-section  of  the  ovary,  x  2.  C,  dia- 
gram of  the  flower.  D,  leaf  and  fruit  of  bitter-sweet  (Celastrus),  x  y2.  ]£t 
fruit  opening  and  disclosing  the  seeds.  F,  section  of  a  nearly  ripe  fruit, 
showing  the  seeds  surrounded  by  the  scarlet  integument  (aril),  em.  the 
embryo,  x  1.  G,  flower  of  grape-vine,  Vitis  (Vitacese),  x  2.  The  corolla 
has  fallen  off.  H,  vertical  section  of  the  pistil,  x  2.  /,  nearly  ripe  fruits 
of  the  frost-grape,  x  1.  J,  cross-section  of  young  fruit,  x  2.  K,  a  spurge, 
Euphorbia  (Euphorbiacese) ,  x  %.  L,  single  group  of  flowers,  surrounded  by 
the  corolla-like  involucre,  x  3.  M,  section  of  the  same.  <?,  male  flowers ; 
9 ,  female  flowers.  N,  a  single  male  flower,  x  5.  0,  cross-section  of  ovary, 
x  6.  P,  a  seed,  x  2.  Q,  longitudinal  section  of  the  seed,  x  3.  em.  embryo. 


poisonous.  This  juice  in  a  number  of  tropical  genera  is  the 
source  of  India-rubber.  Some  genera  like  the  castor-bean 
(Ricinus)  and  Croton  are  cultivated  for  their  large,  showy 
leaves. 

The   water   starworts   (Callitriche) ,  not  uncommon  in  stag- 


CLASSIFICATION   OF  DICOTYLEDONS. 


201 


nant  water,  represent  the  family  Callitrichacece,  and  the  box 
(Buxus)  is  the  type  of  the  Buxacece. 

The  last  and  highest  group  of  the  Choripetalce,  the  Calyci- 
florce,  embraces  a  very  large  assemblage  of  familiar  plants, 
divided  into  eight  orders  and  thirty-two  families.  With  few 


FIG.  110. —  Types  of  Calyciflorse  (Umbelliflorse).  A,  inflorescence  of  wild 
parsnip,  Pastinaca  ( Umbelliferss) ,  x  y2.  J5,  single  flower  of  the  same,  x  3. 
C,  a  leaf,  showing  the  sheathing  hase,  x  14.  D,  a  fruit,  x  2.  E,  cross-section 
of  D.  F,  part  of  the  inflorescence  of  spikenard,  Aralia  (Araliacese),  x  1. 
G,  a  single  flower  of  the  same,  x  3.  H,  the  fruit,  x  2.  /,  cross-section  of  the 
H.  J,  inflorescence  of  dogwood,  Cornus  (Corness).  The  cluster  of  flowers 
is  surrounded  hyfour  white  bracts  (6),  x  y3.  K,  a  single  flower  of  the  same, 
x  2.  L,  diagram  of  the  flower.  M,  young  fruit  of  another  species  (Cornus 
stolonifera)  (red  osier),  x  2.  N,  cross-section  of  M. 

exceptions,  the  floral  axis  grows  up  around  the  ovary,  carrying 
the  outer  floral  leaves  above  it,  and  the  ovary  appears  at  the 
bottom  of  a  cup  around  whose  edge  the  other  parts  of  the 
flower  are  arranged.  Sometimes,  as  in  the  fuchsia,  the  ovary 
is  grown  to  the  base  of  the  cup  or  tube,  and  thus  looks  as  if  it 
were  outside  the  flower.  Such  an  ovary  is  said  to  be  "  inferior" 


202  BOTANY. 

in  distinction  from  one  that  is  entirely  free  from  the  tube,  and 
thus  is  evidently  within  the  flower.  The  latter  is  the  so-called 
" superior"  ovary.  The  carpels  are  usually  united  into  a 
compound  pistil,  but  may  be  separate,  as  in  the  stonecrop 
(Fig.  Ill,  E,)  or  strawberry  (Fig.  114,  (7). 

The  first  order  of  the  Catycijlorce  (Umbellijlorce)  has  the 
flowers  small,  and  usually  arranged  in  umbels,  i.e.  several 
stalked  flowers  growing  from  a  common  point.  The  ovary 
is  inferior,  and  there  is  a  nectar-secreting  disc  between  the 
styles  and  the  stamens.  Of  the  three  families,  the  umbel- 
worts  or  Umbelliferce  is  the  commonest.  The  flowers  are  much 
alike  in  all  (Fig.  110,  A,  B),  and  nearly  all  have  large,  com- 
pound leaves  with  broad,  sheathing  bases.  The  stems  are 
generally  hollow.  So  great  is  the  uniformity  of  the  flowers 
and  plant,  that  the  fruit  (Fig.  110,  D)  is  generally  necessary 
before  the  plant  can  be  certainly  recognized.  This  is  two- 
seeded  in  all,  but  differs  very  much  in  shape  and  in  the  devel- 
opment of  oil  channels,  which  secrete  the  peculiar  oil  that  gives 
the  characteristic  taste  to  the  fruits  of  such  forms  as  caraway, 
coriander,  etc.  Some  of  them,  like  the  wild  parsnip,  poison 
hemlock,  etc.,  are  violent  poisons,  while  others  like  the  carrot 
are  perfectly  wholesome. 

The  wild  spikenard  (Aralia)  (Fig.  110,  F),  ginseng,  and 
the  true  ivy  (Hedera)  are  examples  of  the  Aratiacece,  and  the 
various  species  of  dogwood  (Cornus)  (Fig.  110,  J-N)  repre- 
sent the  dogwood  family  (  Cornece) . 

The  second  order  (Saxifragince)  contains  eight  families, 
including  a  number  of  common  wild  and  cultivated  plants. 
The  true  saxifrages  are  represented  by  several  wild  and  culti- 
vated species  of  Saxifraga,  the  little  bishop's  cap  or  mitre- 
wort  (Mitella)  (Fig.  Ill,  D),  and  others.  The  wild  hydrangea 
(Fig.  Ill,  F)  and  the  showy  garden  species  represent  the 
family  Hydrangece.  In  these  some  of  the  flowers  are  large 
and  showy,  but  with  neither  stamens  nor  pistils  (neutral), 
while  the  small,  inconspicuous  flowers  of  the  central  part  of 


CLASSIFICATION   OF  DICOTYLEDONS. 


203 


the  inflorescence  are  perfect.  In  the  garden  varieties,  all  of 
the  flowers  are  changed,  by  selection,  into  the  showy,  neutral 
ones.  The  syringa  or  mock  orange  (Philadelphus)  (Fig.  Ill, 
7),  the  gooseberry,  and  currants  (Eibes)  (Fig.  Ill,  A),  and 
the  stonecrop  (Sedum)  (Fig.  Ill,  E)  are  types  of  the  families 
Philadelphece,  Hibesiece,  and  Crassulacece. 


FIG.  111. —  Calyciflorse  (Saxifraginse) :  A,  flowers  and  leaves  of  wild  goose- 
berry, Ribes  (Ribesiess),  x  1.  B,  vertical  section  of  the  flower,  x  2.  (7, 
diagram  of  the  flower.  D,  flower  of  bishop's-cap,  Mitella  (tiaxifrayacese) , 
x  3.  E,  flower  of  stonecrop,  Sedum  (Crassulacese),  x  2.  F,  flowers  and 
leaves  of  hydrangea  (Hydrangeae) ,  x  %.  n,  neutral  flower.  G,  unopened 
flower,  x  2.  H,  the  same,  after  the  petals  have  fallen  away.  I,  flower  of 
syringa,  Philadelphus  (Philadelphese) ,  x  1.  J,  diagram  of  the  flower. 

The  third  order  (Opuntiece)  has  but  a  single  family,  the 
cacti  (Cactacece).  These  are  strictly  American  in  their  distri- 
bution, and  inhabit  especially  the  dry  plains  of  the  southwest, 
where  they  reach  an  extraordinary  development.  They  are 
nearly  or  quite  leafless,  and  the  fleshy,  cylindrical,  or  flattened 
stems  are  usually  beset  with  stout  spines.  The  flowers  (Fig. 


204 


BOTANY. 


112,  A)  are  often  very  showy,  so  that  many  species  are  culti- 
vated for  ornament  and  are  familiar  to  every  one.  The  beau- 
tiful night-blooming  cereus,  of  which  there  are  several  species, 
is  one  of  these.  A  few  species  of  prickly-pear  (Opuntia)  occur 
as  far  north  as  New  York,  but  most  are  confined  to  the  hot, 
dry  plains  of  the  south  and  southwest. 


FIG.  112.—  Calyciflorse,  Opuntiese  (Passiflorinss') .  A,  flower  of  a  cactus, 
Mamillaria  (Cactacese)  (from  "Gray's  Structural  Botany").  B,  leaf  and 
flower  of  a  passion-flower,  Passiflora  (Passifloracese) ,  x  %,  t,  a  tendril.  C, 
cross-section  of  the  ovary,  x  2.  D,  diagram  of  the  flower. 

The  fourth  order  (Passiflorince)  are  almost  without  excep- 
tion tropical  plants,  only  a  very  few  extending  into  the 
southern  United  States.  The  type  of  the  order  is  the  passion- 
flower (Passiflora)  (Fig.  112,  B),  whose  numerous  species  are 
mostly  inhabitants  of  tropical  America,  but  a  few  reach  into 
the  United  States.  The  only  other  members  of  the  order 
likely  to  be  met  with  by  the  student  are  the  begonias,  of 
which  a  great  many  are  commonly  cultivated  as  house  plants 


CLASSIFICATION   OF  DICOTYLEDONS. 


205 


on  account  of  their  fine  foliage  and  flowers.  The  leaves  are 
always  one-sided,  and  the  flowers  monoecious.1  Whether  the 
begonias  properly  belong  with  the  Passiflorinw  has  been  ques- 
tioned. 

The  fifth  order  (Myrtiflorm)  have  regular  four-parted  flowers 
with  usually  eight  stamens,  but  sometimes,  through  branching 

D 


FIG.  113.  —  CalyciflorsR  (Myrtiflorse,  Thymelinse).  A,  flowering  branch  of 
moosewood,  Direct  (Thymeleaceas) ,  x  1.  B,  a  single  flower,  x  2.  C,  the 
same,  laid  open.  D,  a  young  flower  of  willow  herb,  Epilobium  (Onagracese) , 
x  1.  The  pistil  (r/y.)  is  not  yet  ready  for  pollination.  E,  an  older  flower, 
with  receptive  pistil.  F,  an  unopened  bud,  x  1.  G,  cross-section  of  the 
ovary,  x  4.  H ,  a  young  fruit,  x  1.  J,  diagram  of  the  flower.  J,  flowering 
branch  of  water  milfoil,  Myriophyllum  (Haloragidacese) ,  x  %.  K,  a  single 
leaf,  x  l.  L,  female  flowers  of  the  same,  x  2.  M,  the  fruit,  x  2. 

of  the  stamens,  these  appear  very  numerous.  The  myrtle  family, 
the  members  of  which  are  all  tropical  or  sub-tropical,  gives  name 
to  the  order.  The  true  myrtle  (Myrtus)  is  sometimes  cultivated 
for  its  pretty  glossy  green  leaves  and  white  flowers,  as  is  also 

1  Monoecious  :  having  stamens  and  carpels  in  different  flowers,  but  on 
the  same  plant. 


206  BOTANY. 

the  pomegranate  whose  brilliant,  scarlet  flowers  are  extremely 
ornamental.  Cloves  are  the  dried  flower-buds  of  an  East- 
Indian  myrtaceous  tree  ( Caryophyllus) .  In  Australia  the 
order  includes  the  giant  gum-trees  (Encalypus),  the  largest  of 
all  known  trees,  exceeding  in  size  even  the  giant  trees  of 
California. 

Among  the  commoner  Myrtifloraz,  the  majority  belong  to 
the  two  families  Onagracece  and  Lythracece.  The  former 
includes  the  evening  primroses  (CEnothera),  willow-herb  (Epi- 
lobium)  (Fig.  113,  D),  and  fuchsia;  the  latter,  the  purple 
loosestrife  (Lythrum)  and  swamp  loosestrife  (Nescea).  The 
water-milfoil  (Myriophyllum)  (Fig.  113,  J)  is  an  example  of 
the  family  Haloragidacece,  and  the  Rhexias  of  the  eastern 
United  States  represent  with  us  the  family  Melastomacece. 

The  sixth  order  of  the  Calyciftorce  is  a  small  one  (Thyme- 
Hnce),  represented  in  the  United  States  by  very  few  species. 
The  flowers  are  four-parted,  the  calyx  resembling  a  corolla, 
which  is  usually  absent.  The  commonest  member  of  the 
order  is  the  moosewood  (Dirca)  (Fig.  113,  A),  belonging  to  the 
first  of  the  three  families  ( Thymelceacece) .  Of  the  second 
family  (Elceagnacece) ,  the  commonest  example  is  Shepherdia, 
a  low  shrub  having  the  leaves  covered  with  curious,  scurfy 
hairs  that  give  them  a  silvery  appearance.  The  third  family 
(Proteacece)  has  no  familiar  representatives. 

The  seventh  order  (JRosiflorce)  includes  many  well-known 
plants,  all  of  which  may  be  united  in  one  family  (Rosacece), 
with  several  sub-families.  The  flowers  are  usually  five-parted 
with  from  five  to  thirty  stamens,  and  usually  numerous,  distinct 
carpels.  In  the  apple  and  pear  (Fig.  114,  /),  however,  the 
carpels  are  more  or  less  grown  together ;  and  in  the  cherry, 
peach,  etc.,  there  is  but  a  single  carpel  giving  rise  to  a  single- 
seeded  stone-fruit  (drupe)  (Fig.  114,  E,  H).  In  the  straw- 
berry (Fig.  114,  A),  rose  (G),  cinquefoil  (Potentilla),  etc., 
there  are  numerous  distinct,  one-seeded  carpels,  and  in 
Spirwa  (Fig.  114,  F)  there  are  five  several-seeded  carpels, 


CLASSIFICATION   OF  DICOTYLEDONS. 


207 


forming  as  many  dry  pods  when  ripe.  The  so-called  "  berry  " 
of  the  strawberry  is  really  the  much  enlarged  flower  axis,  or 
"  receptacle,"  in  which  the  little  one-seeded  fruits  are  embedded, 
the  latter  being  what  are  ordinarily  called  the  seeds. 

From  the  examples  given,  it  will  be  seen  that  the  order 
includes  not  only  some  of  the  most  ornamental,  cultivated 


FIG.  114.—  Calyciflorse  (Rosiflorse).  A,  inflorescence  of  strawberry  (Fra- 
c/aria),  x  %.  J5,  a  single  flower,  x  1.  (7,  section  of  B.  D,  floral  diagram. 
E,  vertical  section  of  a  cherry-flower  (Prunus),  x  1.  F,  vertical  section  of 
the  flower  of  Spirsea,  x  2.  G,  vertical  section  of  the  bud  of  a  wild  rose 
(Rosa),  x  1.  H,  vertical  section  of  the  young  fruit,  x  1.  /,  section  of  the 
flower  of  an  apple  (Pyrus),  x  1.  J,  floral  diagram  of  apple. 

plants,  but  the  majority  of  our  best  fruits.  In  addition  to 
those  already  given,  may  be  mentioned  the  raspberry,  black- 
berry, quince,  plum,  and  apricot. 

The  last  order  of  the  Calyciflorce  and  the  highest  of  the 
Choripetalce  is  the  order  Leguminosce,  of  which  the  bean, 
pea,  clover,  and  many  other  common  plants  are  examples.  In 
most  of  our  common  forms  the  flowers  are  peculiar  in  shape, 


208 


BOTANY. 


one  of  the  petals  being  larger  than  the  others,  and  covering 
them  in  the  bud.  This  petal  is  known  as  the  standard.  The 
two  lateral  petals  are  known  as  the  wings,  and  the  two  lower 
and  inner  are  generally  grown  together  forming  what  is  called 
the  "keel"  (Fig.  115,  A,  B).  The  stamens,  ten  in  number, 


FIG.  115. —  Calyciflorx  (Leguminossi) .  A,  flowers  and  leaf  of  the  common 
pea,  Pisum  (Papilionacese),  x  %.  t,  tendril,  st.  stipules.  B,  the  petals, 
separated  and  displayed,  x  1.  C,  flower,  with  the  calyx  and  corolla  removed, 
x  1.  1),  a  fruit  divided  lengthwise,  x  V2.  E,  the  embryo,  with  one  of  the 
cotyledons  removed,  x  2.  F,  diagram  of  the  flower.  G,  flower  of  red-bud, 
Cercis  (Csesalpinacese) ,  x  2.  H,  the  same,  with  calyx  and  corolla  removed. 
/,  inflorescence  of  the  sensitive-brier,  Schrankia  (Mimosacese),  x  1.  «7,  a 
single  flower,  x  2. 

are  sometimes  all  grown  together  into  a  tube,  but  generally 
the  upper  one  is  free  from  the  others  (Fig.  115,  (7).  There  is 
but  one  carpel  which  forms  a  pod  with  two  valves  when  ripe 
(Fig.  115,  D).  The  seeds  are  large,  and  the  embryo  fills  the 
seed  completely.  From  the  peculiar  form  of  the  flower,  they 
are  known  as  Papilionacece  (papilio,  a  butterfly).  Many  of 


CLASSIFICATION   OF  DICOTYLEDONS.  209 

the  Papilionacece  are  climbers,  either  having  twining  stems,  as 
in  the  common  beans,  or  else  with  part  of  the  leaf  changed 
into  a  tendril  as  in  the  pea  (Fig.  115,  A)y  vetch,  etc.  The 
leaves  are  usually  compound. 

Of  the  second  family  (Ccesalpinece),  mainly  tropical,  the  honey 
locust  (Gleditschia)  and  red-bud  (Cercis)  (Fig.  115,  (2)  are 
the  commonest  examples.  The  flowers  differ  mainly  from  the 
Papilionacece  in  being  less  perfectly  papilionaceous,  and  the 
stamens  are  almost  entirely  distinct  (Fig.  115,  H).  The  last 
family  (Mimosacece)  is  also  mainly  tropical.  The  acacias, 
sensitive-plant  (Mimosa),  and  the  sensitive-brier  of  the  south- 
ern United  States  (Schrankia)  (Fig.  115,  /)  represent  this 
family.  The  flowers  are  quite  different  from  the  others  of 
the  order,  being  tubular  and  the  petals  united,  thus  resembling 
the  flowers  of  the  Sympetalce.  The  leaves  of  Mimosa  and 
Schrarikia  are  extraordinarily  sensitive,  folding  up  if  irritated. 


CHAPTER   XIX. 

CLASSIFICATION   OF  DICOTYLEDONS  (Continued}. 
DIVISION  II.  —  Sympetalce. 

THE  Sympetalce  or  Gamopetalce  are  at  once  distinguished 
from  the  Choripetalce  by  having  the  petals  more  or  less  united, 
so  that  the  corolla  is  to  some  extent  tubular.  In  the  last  order 
of  the  Choripetalce  we  found  a  few  examples  (Mimosacecv) 
where  the  same  thing  is  true,  and  these  form  a  transition  from 
the  Choripetalce  to  the  Sympetalce. 

There  are  two  great  divisions,  Isocarpce  and  Anisocarpce.  In 
the  first  the  carpels  are  of  the  same  number  as  the  petals  and 
sepals ;  in  the  second  fewer.  In  both  cases  the  carpels  are 
completely  united,  forming  a  single,  compound  pistil.  In  the 
Isocarpce  there  are  usually  twice  as  many  stamens  as  petals, 
occasionally  the  same  number. 

There  are  three  orders  of  the  Isocarpcej  viz.,  Bicornes,  Pri- 
mulince,  and  Diospyrince.  The  first  is  a  large  order  with  six 
families,  including  many  very  beautiful  plants,  and  a  few  of 
some  economic  value.  Of  the  six  families,  all  but  one  (Epa- 
cridece)  are  represented  in  the  United  States.  Of  these  the 
Pyrolacece  includes  the  pretty  little  pyrolas  and  prince's-pine 
(  Chimaphila)  (Fig.  116,  J)  ;  the  Monotropece  has  as  its  common- 
est examples,  the  curious  Indian-pipe  (Monotropa  uniflora), 
and  pine-sap  (M.  hypopitys)  (Fig.  116,  L).  These  grow  on 
decaying  vegetable  matter,  and  are  quite  devoid  of  chlorophyll, 
the  former  species  being  pure  white  throughout  (hence  a  popu- 
lar name,  "ghost  flower")  ;  the  latter  is  yellowish.  The  mag- 
nificent rhododendrons  and  azaleas  (Fig.  116,  F),  and  the 
mountain  laurel  (Kalmia)  (Fig.  116,  /),  belong  to  the  Rhodo- 
210 


CLASSIFICATION   OF  DICOTYLEDONS. 


211 


racece.  The  heath  family  (Ericaceae),  besides  the  true  heaths 
(Erica,  Calluna),  includes  the  pretty  trailing-arbutus  or  may- 
flower  (Epigcea),  Andromeda,  Oxydendram  (Fig.  116,  E), 
wintergreeii  (Gaultheria),  etc.  The  last  family  is  represented 
by  the  cranberry  (Vaccinium)  and  huckleberry  (Gaylussacia) . 


FIG.  116. — Types  of  Isocarpous  sympetalse  (Bicornes).  A,  flowers,  fruit,  and 
leaves  of  huckleberry,  Gaylussacia  (Vacciniess) ,  x  1.  B,  vertical  section  of 
the  flower,  x  3.  (7,  a  stamen :  i,  from  in  front ;  ii,  from  the  side,  x  4.  D, 
cross-section  of  the  young  fruit,  x  2.  E,  flower  of  sorrel-tree,  Oxydendrum 
(Ericacese),  x  2.  F,  flower  of  azalea  (Rhododendron),  x  %.  G,  cross-section 
of  the  ovary,  x  3.  11,  diagram  of  the  flower.  /,  flower  of  mountain  laurel 
(Kalmia),  x  1.  J,  prince's-pine,  Chimaphila  (Pyrolacese) ,  x  y2.  K,  a  single 
flower,  x  1.  L,  plant  of  pine-sap,  Monotropa,  (Monot ropeds) ,  x  l/2.  M,  section 
of  a  flower,  x  1. 

The  second  order,  the  primroses  (Primulince),  is  principally 
represented  in  the  cooler  parts  of  the  world  by  the  true  prim- 
rose family  (Primulacece),  of  which  several  familiar  plants  may 
be  mentioned.  The  genus  Primula  includes  the  European 
primrose  and  cowslip,  as  well  as  two  or  three  small  American 
species,  and  the  commonly  cultivated  Chinese  primrose.  Other 


212 


BOTANY. 


genera  are  Dodecatlieon,  of  which  the  beautiful  shooting-star 
(D.  Meadia)  (Fig.  117,  A)  is  the  best  known.  Something 
like  this  is  Cyclamen,  sometimes  cultivated  as  a  house  plant. 
The  moneywort  (Lysimachia  nummularia)  (Fig.  117,  D),  as 
well  as  other  species,  also  belongs  here. 


cm. 


FIG.  117.  —  IsocarpoKS  sympetalse  (Primulinse,  Diospy  rinse).  A,  shooting- 
star,  Dodecatheon  (Prirmdacese) ,  x  %.  B,  section  of  a  flower,  x  l.  C,  dia- 
gram of  the  flower.  D,  Moneywort,  Lysimachia  (Prinwlacese) ,  x  %.  E,  a 
perfect  flower  of  the  persimmon,  Diospyros  (Ebenacese),  x  1.  F,  the  same, 
laid  open  :  section  of  the  young  fruit,  x  2.  //,  longitudinal  section  of  a  ripe 
seed,  x  1.  em.  the  embryo.  /,  fruit,  x  %. 

The  sea-rosemary  (Statice)  and  one  or  two  cultivated  species 
of  plumbago  are  the  only  members  of  the  plumbago  family 
(Plumbaginece)  likely  to  be  met  with.  The  remaining  families 
of  the  Primulince  are  not  represented  by  any  common  plants. 

The  third  and  last  order  of  the  Isocarpous  sympetalce  has 
but  a  single  common  representative  in  the  United  States ;  viz., 
the  persimmon  (Diospyros)  (Fig.  117,  E).  This  belongs  to 
the  family  Ebenacece,,  to  which  also  belongs  the  ebony  a 


CLASSIFICATION   OF  DICOTYLEDONS. 


213 


member  of  the  same  genus  as  the  persimmon,  and  found  in 
Africa  and  Asia. 

The  second  division  of  the  Sympetalce  (the  Anisocarpce)  has 
usually  but  two  or  three  carpels,  never  as  many  as  the  petals. 
The  stamens  are  also  never  more  than  five,  and  very  often  one 
or  more  are  abortive. 


FIG.  118.  —  Types  of  Anisocarpous  sympetalss  (TubiflorsR).  A,  flower  and 
leaves  of  wild  phlox  (Polemoniacese),  x  %.  J3,  section  of  a  flower,  x  l.  C, 
fruit,  x  1.  Dy  flower  of  blue  valerian  (Polemonfarri) ,  x  1.  E,  flowers  and 
leaf  of  water-leaf,  Hydrophyllum  (Hydrophyllacesd),  x  %.  F,  section  of  a 
flower,  x  1.  G,  flower  of  wild  morning-glory,  Convolvulus  ( Convolvulacese) , 
x  %.  One  of  the  bracts  surrounding  the  calyx  and  part  of  the  corolla  are  cut 
away.  H,  diagram  of  the  flower.  /,  the  fruit  of  a  garden  morning-glory, 
from  which  the  outer  wall  has  fallen,  leaving  only  the  inner  membranous 
partitions,  x  l.  ,/,  a  seed,  x  1.  K,  cross-section  of  a  nearly  ripe  seed,  show- 
ing the  crumpled  embryo,  x  2.  L,  an  embryo  removed  from  a  nearly  ripe 
seed,  and  spread  out ;  one  of  the  cotyledons  has  been  partially  removed,  x  1. 

The  first  order  (Tubiflorce)  has,  as  the  name  indicates, 
tubular  flowers  which  show  usually  perfect,  radial  symmetry 
(Actinomorphism) .  There  are  five  families,  all  represented  by 
familiar  plants.  The  first  (Convolvulacece)  has  as  its  type  the 
morning-glory  (Convolvulus)  (Fig.  118,  G),  and  the  nearly 


214 


BOTANY. 


related  Ipomoeas  of  the  gardens.  The  curious  dodder  (Cuscuta), 
whose  leafless,  yellow  stems  are  sometimes  very  conspicuous, 
twining  over  various  plants,  is  a  member  of  this  family  which 
has  lost  its  chlorophyll  through  parasitic  habits.  The  sweet 
potato  (Batatas)  is  also  a  member  of  the  morning-glory  family. 
The  numerous  species,  wild  and  cultivated,  of  phlox  (Fig.  118, 


FIG.  119.  —  Anisocarpous  sympetalx  (Tubiflorse).  A,  inflorescence  of  hound's- 
tongue,  Cynoylossum  (Borrayinese) ,  x  %.  B,  section  of  a  flower,  x  2.  C, 
nearly  ripe  fruit,  x  1.  /),  flowering  branch  of  nightshade,  Solanum 
(Solancse),  x  V2.  E,  a  single  flower,  x  i.  F,  section  of  the  flower,  x  2.  G, 
young  fruit,  x  1.  H,  flower  of  Petunia  (Solanex) ,  x  %.  I,  diagram  of  the 
flower. 

A),  and  the  blue  valerian  (Polemonium)  (Fig.  118,  D),  are 
examples  of  the  family  Polemoniacece. 

The  third  family  (Hydrophyllacece)  includes  several  species 
of  water-leaf  (Hydropliyllum)  (Fig.  118,  E)  and  Phacelia,  among 
our  wild  flowers,  and  species  of  Nemophila,  Whitlavia  and 
others  from  the  western  states,  but  now  common  in  gardens, 


CLASSIFICATION   OF  DICOTYLEDONS.  215 

The  Borage  family  (Borraginece)  includes  the  forget-me-not 
(Myosotis)  and  a  few  pretty  wild  flowers,  e.g.  the  orange-flow- 
ered puccoons  (Lithospernum)  ;  but  it  also  embraces  a  number 
of  the  most  troublesome  weeds,  among  which  are  the  houndV 
tongue  (Cynoglossum)  (Fig.  119,  A),  and  the  " beggar' s-ticks " 
(Echinospernum),  whose  prickly  fruits  (Fig.  119,  C)  become 
detached  on  the  slightest  provocation,  and  adhere  to  whatever 
they  touch  with  great  tenacity.  The  flowers  in  this  family 
are  arranged  in  one-sided  inflorescences  which  are  coiled  up  at 
first  and  straighten  as  the  flowers  expand. 

The  last  family  (Solanece)  includes  the  nightshades  (Sola- 
num)  (Fig.  119,  J9),  to  which  genus  the  potato  ($.  tuberosum) 
and  the  egg-plant  (S.  Melongena)  also  belong.  Many  of  the 
family  contain  a  poisonous  principle,  e.g.  the  deadly  night- 
shade (Atropa),  tobacco  (Nicotiana) ,  stramonium  (Datura), 
and  others.  Of  the  cultivated  plants,  besides  those  already 
mentioned,  the  tomato  (Lycopersicum) ,  and  various  species  of 
Petunia  (Fig.  119,  JET),  Solanum,  and  Datura  are  the  commonest. 

The  second  order  of  the  Anisocarpce  consists  of  plants  whose 
flowers  usually  exhibit  very  marked,  bilateral  symmetry 
(Zygomorphism) .  From  the  flower  often  being  two-lipped 
(see  Fig.  120),  the  name  of  the  order  (Labiatijtorce)  is  derived. 

Of  the  nine  families  constituting  the  order,  all  but  one  are 
represented  within  our  limits,  but  the  great  majority  belong 
to  two  families,  the  mints  (Labiatce)  and  the  figworts  (Scroph- 
ularinece).  The  mints  are  very  common  and  easily  recogniz- 
able on  account  of  their  square  stems,  opposite  leaves,  strongly 
bilabiate  flowers,  and  the  ovary  splitting  into  four  seed-like 
fruits  (Fig.  120,  D,  F). 

The  great  majority  of  them,  too,  have  the  surface  covered  with  glandu- 
lar hairs  secreting  a  strong- scented  volatile  oil,  giving  the  peculiar  odor 
to  these  plants.  The  dead  nettle  (Lamium)  (Fig.  120,  A)  is  a  thoroughly 
typical  example.  The  sage,  mints,  catnip,  thyme,  lavender,  etc.,  will 
recall  the  peculiarities  of  the  family. 


216 


BOTANY. 


The  stamens  are  usually  four  in  number  through  the  abor- 
tion of  one  of  them,  but  sometimes  only  two  perfect  stamens 
are  present. 

The  Scrophularinece  differ  mainly  from  the  Labiatce  in  hav- 
ing round  stems,  and  the  ovary  not  splitting  into  separate  one- 


FIG.  120.  —  Anisocarpous  sympetalse,  (Labiatiflorse) .  A,  dead  nettle,  Lamium, 
(Labiatse),  x  %.  Bt  a  single  flower,  x  l.  C,  the  stamens  and  pistil,  x  1.  D, 
cross-section  of  the  ovary,  x  2.  E,  diagram  of  the  flower ;  the  position  of  the 
absent  stamen  is  indicated  by  the  small  circle.  F,  fruit  of  the  common  sage, 
Salvia  (Labiatse) ,  x  1.  Part  of  the  persistent  calyx  has  been  removed  to 
show  the  four  seed-like  fruits,  or  nutlets.  G,  section  of  a  nutlet,  x  3.  The 
embryo  fills  the  seed  completely.  H,  part  of  an  inflorescence  of  figwort, 
Scrophularia  (Scrophularinese) ,  x  1.  /,  cross-section  of  the  young  fruit, 
x  2.  J,  flower  of  speedwell,  Veronica  (Scrophularinese) ,  x  2.  K,  fruit  of 
Veronica,  x  2.  L,  cross-section  of  K,  M,  flower  of  moth-mullein,  Ver- 
bascum  (ScrophularinesR),  x  %.  2i,  flower  of  toad-flax,  Linaria  (Scrophii- 
larinese),  x  1.  O,  leaf  of  bladder-weed,  Utricularia  (Lentibulariacese] ,  x  1. 
x,  one  of  the  "traps."  P,  a  single  trap,  x  5. 

seeded  fruits.  The  leaves  are  also  sometimes  alternate.  There 
are  generally  four  stamens,  two  long  and  two  short,  as  in  the 
labiates,  but  in  the  mullein  (Verbascum)  (Fig.  120,  M),  where 
the  flower  is  only  slightly  zygomorphic,  there  is  a  fifth  rudi- 


CLASSIFICATION   OF  DICOTYLEDONS. 


217 


mentary  stamen,  while  in  others  (e.g.  Veronica)  (Fig.  120,  J) 
there  are  but  two  stamens.  Many  have  large,  showy  flowers, 
as  in  the  cultivated  foxglove  (Digitalis),  and  the  native  species 
of  Gerardia,  mullein,  Mimulus,  etc.,  while  a  few  like  the 


FIG.  121.  —  Anisocarpons  sympetalse  (Labiatiflorse) .  A,  flowering  branch  of 
trumpet-creeper,  Tecoma  (Bignoniacese) ,  x  y4.  .B/a  single  flower,  divided 
lengthwise,  x  %,  C,  cross-section  of  the  ovary,  x  2.  1),  diagram  of  the 
flower.  E,  flower  of  vervain,  Verbena  (Verbense},  x  2:  i,  from  the  side; 
n,  from  in  front ;  in,  the  corolla  laid  open.  F,  nearly  ripe  fruit  of  the  same, 
x  2.  G,  part  of  a  spike  of  flowers  of  the  common  plantain,  Plantayo 
(Plantaginese),  x  1.  The  upper  flowers  have  the  pistils  mature,  but  the 
stamens  are  not  yet  ripe.  H,  a  flower  from  the  upper  (younger)  part  of  the 
spike.  /,  an  older  expanded  flower,  with  ripe  stamens,  x  3. 

figwort,  Scropliularia  (Fig.  120,  H),  and  speedwells  ( Veronica), 
have  duller-colored  or  smaller  flowers. 

The  curious  bladder-weed  (Utricularia)  is  the  type  of  the 
family  Lentibulariacece,  aquatic  or  semi-aquatic  plants  which 
possess  special  contrivances  for  capturing  insects  or  small 
water  animals.  These  in  the  bladder-weed  are  little  sacs  (Fig. 


218  BOTANY. 

120,  P)   which  act  as  traps  from  which  the  animals  cannot 
escape  after  being  captured.     There  does  not  appear  to  be 
here  any  actual  digestion,  but  simply  an  absorption  of  the 
products  of  decomposition,  as  in  the  pitcher-plant.     In  the 
nearly  related  land  form,  Pinguicula,  however,  there  is  much 
the  same  arrangement  as  in  the  sundew. 

The  family  Gesneracece  is  mainly  a  tropical  one,  repre- 
sented in  the  greenhouses  by  the  magnificent  Gloxinia  and 
Achimenes,  but  of  native  plants  there  are  only  a  few  parasitic 
forms  destitute  of  chlorophyll  and  with  small,  inconspicuous 
flowers.  The  commonest  of  these  is  Epiphegus,  a  much- 
branched,  brownish  plant,  common  in  autumn  about  the  roots 
of  beech-trees  upon  which  it  is  parasitic,  and  whence  it  derives 
its  common  name,  "beech-drops." 

The  bignonia  family  (Bignoniacece)  is  mainly  tropical,  but 
in  our  southern  states  is  represented  by  the  showy  trumpet- 
creeper  (Tecoma)  (Fig.  121,  A),  the  catalpa,  and  Martynia. 

The  other  plants  likely  to  be  met  with  by  the  student 
belong  either  to  the  Verbenacece,  represented  by  the  showy 
verbenas  of  the  gardens,  and  our  much  less  showy  wild  ver- 
vains, also  belonging  to  the  genus  Verbena  (Fig.  121,  E)  ; 
or  to  the  plantain  family  (Plantaginece) ,  of  which  the  various 
species  of  plantain  (Plantago)  are  familiar  to  every  one  (Fig. 

121,  G,  I).     The  latter  seem  to  be  forms  in  which  the  flowers 
have   become   inconspicuous,  and   are  wind  fertilized,  while 
probably  all  of  its  showy-flowered  relatives  are  dependent  on 
insects  for  fertilization. 

The  third  order  (Contortce)  of  the  Anisocarpce  includes  five 
families,  all  represented  by  familiar  forms.  The  first,  the  olive 
family  (0/eaceee),  besides  the  olive,  contains  the  lilac  and 
jasmine  among  cultivated  plants,  and  the  various  species  of 
ash  (Fraxinus),  and  the  pretty  fringe-tree  (Chionanthus)  (Fig. 

122,  A)}  often  cultivated  for  its  abundant  white  flowers.     The 
other  families  are  the  Gentianacece  including  the  true  gentians 
(Gentiana)    (Fig.   122,  F),  the  buck-bean  (Menyanthes) ,  the 


CLASSIFICATION  OF  DICOTYLEDONS. 


219 


centauries  (Erythercea  and  Sabbatia),  and  several  other  less 
familiar  genera ;  Loganiacece,  with  the  pink-root  (Spigelia) 
(Fig.  122,  D),  as  the  best-known  example ;  Apocynacece,  includ- 
ing the  dog-bane  (Apocynum)  (Fig.  122,  H),  and  in  the  gardens 
the  oleander  and  periwinkle  (  Vinca) . 


FIG.  122.  —  Anisocarpous  sympetalse  (Contortse).  A,  flower  of  fringe-tree, 
Chionanthus  (Oleacese),  x  1.  B,  base  of  the  flower,  with  part  of  the  calyx 
and  corolla  removed,  x  2.  C,  fruit  of  white  ash,  Fraxinus  (Oleacese),  x  1. 
D,  flower  of  pink-root,  Spigelia  (Loyaniacese) ,  x  y2.  E,  cross-section  of  the 
ovary,  x  3.  F,  flower  of  fringed  gentian,  Gentiana  (Gentianacese) ,  x  y2. 
G,  diagram  of  the  flower.  H,  flowering  branch  of  dog-bane,  Apocynum 
(Apocynacese) ,  x  %.  J,  vertical  section  of  a  flower,  x  2.  J,  bud.  Jf,  flower 
of  milk-weed,  Asclepias  (Asclepiadacese),  x  1.  L,  vertical  section  through 
the  upper  part  of  the  flower,  x  2.  yy.  pistil,  p,  pollen  masses,  an.  stamen. 
M,  a  pair  of  pollen  masses,  x  6.  N,  a  nearly  ripe  seed,  x  1. 

The  last  family  is  the  milk-weeds  (Asdepiadacece) ,  which 
have  extremely  complicated  flowers.  Our  numerous  milk- 
weeds (Fig.  122,  K)  are  familiar  representatives,  and  exhibit 
perfectly  the  peculiarities  of  the  family.  Like  the  dog-banes, 
the  plants  contain  a  milky  juice  which  is  often  poisonous. 


220 


BOTANY. 


Besides  the  true  milk-weeds  (Asdepias),  there  are  several  other 
genera  within  the  United  States,  but  mostly  southern  in  their 
distribution.  Many  of  them  are  twining  plants  and  occasionally 


J  an. 


FIG.  123.  —  Anisocarpous  sympetalse  (Campanulinse) .  A,  vertical  section  of 
the  bud  of  American  bell-flower,  Campanula  (Campanulacese) ,  x  2.  J3,  an 
expanded  flower,  x  1.  The  stamens  have  discharged  their  pollen,  and  the 
stigma  has  opened.  C,  cross-section  of  the  ovary,  x  3.  JJ,  flower  of  the 
Carpathian  bell-flower  (Campanula  Carpaticd),  x  1.  E,  flower  of  cardinal- 
flower,  Lobelia  (Lobeliacese),  x  1.  F,  the  same,  with  the  corolla  and  sepals 
removed,  an.  the  united  anthers,  f/i/.  the  tip  of  the  pistil.  G,  the  tip  of  the 
pistil,  x  2,  showing  the  circle  of  hairs  surrounding  the  stigma.  H,  cross- 
section  of  the  ovary,  x  3.  /,  tip  of  a  branch  of  cucumber,  Oucttrbita 
(Cvcurbitacese),  with  an  expanded  female  flower  (9).  J,  andrcecium  of  a 
male  flower,  showing  the  peculiar  convoluted  anthers  (an.),  x  2.  K,  cross- 
section  of  the  ovary,  x  2. 


cultivated  for  their  showy  flowers.     Of  the  cultivated  forms, 
the  wax-plant  (Hoy a),  and  Physianthus  are  the  commonest. 

The  fourth  order  (Campanulince)  also  embraces  five  families, 
but  of  these  only  three  are  represented  among  our  wild  plants. 
The  bell-flowers  (Campanula)  (Fig.  123,  A,  D)  are  examples 


CLASSIFICATION   OF  DICOTYLEDONS. 


221 


of  the  family  Campanulacece,  and  numerous  species  are  com- 
mon, both,  wild  and  cultivated. 

The  various  species  of  Lobelia,  of  which  the  splendid  cardi- 
nal-flower (L.  Cardinalis)  (Fig.  123,  E)  is  one  of  the  most 


FIG.  124.  —  Anisocarpous  sympetulse  (Aggregate) .  A,  flowering  branch  of 
Houstonia  purpurea,  x  1  (Rubiacese).  JB,  vertical  section  of  a  flower,  x  2. 
C,  fruit  of  bluets  (Houstonia  ecerufea),  x  i.  J},  cross-section  of  the  same. 
E,  bedstraw,  Galium  (Rubiacese),  x  y2.  F,  a  single  flower,  x  2.  G,  flower 
of  arrow-wood,  Viburnum  (Caprifotiacese),  x*  2.  H,  the  same,  divided 
vertically.  /,  flowering  branch  of  trumpet  honeysuckle,  Loniccera  (Capri- 
foliacese),  x  %.  J,  a  single  flower,  the  upper  part  laid  open,  x  1.  K,  dia- 
gram of  the  flower.  L,  part  of  the  inflorescence  of  valerian,  Valeriana, 
(Valerianese) ,  x  1.  M,  young;  N,  older  flower,  x  2.  0,  cross-section  of  the 
young  fruit;  one  division  of  the  three  contains  a  perfect  seed,  the  others 
are  crowded  to  one  side  by  its  growth.  P,  inflorescence  of  teasel,  Dipsacus 
(Dipxacese),  x  y4.  fl.  flowers.  Q,  a  single  flower,  x  1.  R,  the  same,  with 
the  corolla  laid  open. 

beautiful,  represent  the  very  characteristic  family  Lobeliacem. 
Their  milky  juice  contains  more  or  less  marked  poisonous 
properties.  The  last  family  of  the  order  is  the  gourd  family 
(Cucurbitacece) ,  represented  by  a  few  wild  species,  but  best 
known  by  the  many  cultivated  varieties  of  melons,  cucumbers, 


222 


BOTANY. 


squashes,  etc.  They  are  climbing  or  running  plants,  and  pro- 
vided with  tendrils.  The  flowers  are  usually  unisexual,  some- 
times dioecious,  but  oftener  monoecious  (Fig.  123,  /). 

The  last  and  highest  order  of  the  Sympetalce,  and  hence  of 


FIG.  125.  —  Anisocarpous  sympetalse  (Aggregate).  Types  of  Composite.  A, 
inflorescence  of  Canada  thistle  (Cirsium),  x  1.  B,  vertical  section  of  A.  r, 
the  receptacle  or  enlarged  end  of  the  stem,  to  which  the  separate  flowers  are 
attached.  (7,  a  single  flower,  x  2.  o,  the  ovary,  p,  the  ''pappus"  (calyx 
lobes),  an.  the  united  anthers.  D,  the  upper  part  of  the  stamens  and  pistil, 
x  3  :  i,  from  a  young  flower ;  n,  from  an  older  one.  an.  anthers,  yy.  pistil. 
E,  ripe  fruit,  x  1.  F,  inflorescence  of  may-weed  (Marutu).  The  centra} 
part  (disc)  is  occupied  by  perfect  tubular  flowers  (G),  the  flowers  about  the 
edge  (rays)  are  sterile,  with  the  corolla  much  enlarged  and  white,  x  2.  Q, 
a  single  flower  from  the  disc,  x  3.  H,  inflorescence  of  dandelion  ( Taraxa- 
cum), the  flowers  all  alike,  with  strap-shaped  corollas,  x  1.  /,  a  single 
flower,  x  2.  c,  the  split,  strap-shaped  corolla.  «7,  two  ripe  fruits,  still 
attached  to  the  receptacle  (r).  The  pappus  is  raised  on  a  long  stalk,  x  1. 
K,  a  single  fruit,  x  2. 

the  dicotyledons,  is  known  as  Aggregatce,  from  the  tendency 
to  have  the  flowers  densely  crowded  into  a  head,  which  not 
infrequently  is  closely  surrounded  by  bracts  so  that  the  whole 
inflorescence  resembles  a  single  flower.  There  are  six  families, 


CLASSIFICATION  OF  DICOTYLEDONS.  223 

five  of  which  have  common  representatives,  but  the  last  family 
(Calycerece)  has  no  members  within  our  limits. 

The  lower  members  of  the  order,  e.g.  various  Rubiacece  (Fig. 
124,  A,  -ET),  have  the  flowers  in  loose  inflorescences,  but  as  we 
examine  the  higher  families,  the  tendency  for  the  flowers  to 
become  crowded  becomes  more  and  more  evident,  and  in  the 
highest  of  our  native  forms  Dipsacece  (Fig.  124,  P)  and  Com- 
positce  (Fig.  125)  this  is  very  marked  indeed.  In  the  latter 
family,  which  is  by  far  the  largest  of  all  the  angiosperms, 
including  about  ten  thousand  species,  the  differentiation  is 
carried  still  further.  Among  our  native  Compositor  there  are 
three  well-marked  types.  The  first  of  these  may  be  repre- 
sented by  the  thistles  (Fig.  125,  A).  The  so-called  flower  of 
the  thistle  is  in  reality  a  close  head  of  small,  tubular  flowers 
(Fig.  125,  (7),  each  perfect  in  all  respects,  having  an  inferior 
one-celled  ovary,  five  stamens  with  the  anthers  united,  and  a 
five-parted  corolla.  The  sepals  (here  called  the  "pappus  ")  (p) 
have  the  form  of  fine  hairs.  These  little  flowers  are  attached 
to  the  enlarged  upper  end  of  the  flower  stalk  (receptacle,  r), 
and  are  surrounded  by  closely  overlapping  bracts  or  scale 
leaves  which  look  like  a  calyx;  the  flowers,  on  superficial 
examination,  appear  as  single  petals.  In  other  forms  like 
the  daisy  and  may-weed  (Fig.  125,  F),  only  the  central  flowers 
are  perfect,  and  the  edge  of  the  inflorescence  is  composed  of 
flowers  whose  corollas  are  split  and  flattened  out,  but  the 
stamens  and  sometimes  the  pistils  are  wanting  in  these  so- 
called  "ray-flowers."  In  the  third  group,  of  which  the  dande- 
lion (Fig.  125,  H),  chicory,  lettuce,  etc.,  are  examples,  all  of 
the  flowers  have  strap-shaped,  split  corollas,  and  contain  both 
stamens  and  pistils. 

The  families  of  the  Aggregates  are  the  following :  I.  Rubiacece 
of  which  Houstonla  (Fig.  124,  A),  Galium  (E),  Cephalantlius 
(button-bush),  and  Mitcliella,  (partridge-berry)  are  examples; 
II.  Caprifoliacece,  containing  the  honeysuckles  (Lonicera) 
(Fig.  124,  /),  Viburnum  (6?),  snowberry  (Symphoricarpus), 


224 


BOTANY. 


and  elder  (Sambucus)  ;  III.  Valerianece,  represented  by  the 
common  valerian  ( Valeriana)  (Fig.  124,  L)  ;  IV.  Dipsacece, 
of  which  the  teasel  (Dipsacus)  (Fig.  124,  P),  is  the  type,  and 

also  species  of  scabious 
(Scabiosa)  ;  V.  Com- 
positce,  to  which  the 
innumerable,  so-called 
compound  flowers, 
asters,  golden  -  rods, 
daisies,  sunflowers,  etc. 
belong;  VI.  Calycerece. 
Besides  the  groups 
already  mentioned, 
there  are  several  fam- 
ilies of  dicotyledons 
whose  affinities  are 
very  doubtful.  They 
are  largely  parasitic, 
e.g.  mistletoe ;  or  water 
plants,  as  the  horned 
pond-weed  (Cerato- 
phyllum).  One  family, 
the  Aristolochiacece^ep- 
resented  by  the  curi- 
(Aristolochia  sipho),  a  woody  twiner 


FIG.  I26.  —  Aristolochiacese.  A,  plant  of  wild 
ginger  (Asarum),  x  %.  B,  vertical  sec- 
tion of  the  flower,  x  I.  C,  diagram  of  the 
flower. 


ous  "  Dutchman's  pipe 


with  very  large  leaves,  and  the  common  wild  ginger  (Asarum) 
(Fig.  126),  do  not  appear  to  be  in  any  wise  parasitic,  but  the 
structure  of  their  curious  flowers  differs  widely  from  any  other 
group  of  plants. 


CHAPTER   XX. 

FERTILIZATION   OF  FLOWERS. 

IF  we  compare  the  flowers  of  different  plants,  we  shall  find 
almost  infinite  variety  in  structure,  and  this  variation  at  first 
appears  to  follow  no  fixed  laws ;  but  as  we  study  the  matter 
more  thoroughly,  we  find  that  these  variations  have  a  deep 
significance,  and  almost  without  exception  have  to  do  with  the 
fertilization  of  the  flower. 

In  the  simpler  flowers,  such  as  those  of  a  grass,  sedge,  or 
rush  among  the  monocotyledons,  or  an  oak,  hazel,  or  plantain, 
among  dicotyledons,  the  flowers  are  extremely  inconspicuous 
and  often  reduced  to  the  simplest  form.  In  such  plants, 
the  pollen  is  conveyed  from  the  male  flowers  to  the  female 
by  the  wind,  and  to  this  end  the  former  are  usually  placed 
above  the  latter  so  that  these  are  dusted  with  the  pollen 
whenever  the  plant  is  shaken  by  the  wind.  In  these  plants, 
the  male  flowers  often  outnumber  the  female  enormously,  and 
the  pollen  is  produced  in  great  quantities,  and  the  stigmas 
are  long  and  often  feathery,  so  as  to  catch  the  pollen  readily. 
This  is  very  beautifully  shown  in  many  grasses. 

If,  however,  we  examine  the  higher  groups  of  flowering 
plants,  we  see  that  the  outer  leaves  of  the  flower  become  more 
conspicuous,  and  that  this  is  often  correlated  with  the  develop- 
ment of  a  sweet  fluid  (nectar)  in  certain  parts  of  the  flower, 
while  the  wind-fertilized  flowers  are  destitute  of  this  as  well 
as  of  odor. 

If  we  watch  any  bright-colored  or  sweet-scented  flower  for 
any  length  of  time,  we  shall  hardly  fail  to  observe  the  visits 
of  insects  to  it,  in  search  of  pollen  or  honey,  and  attracted  to 
the  flower  by  its  bright  color  or  sweet  perfume.  In  its  visits 

225 


226  BOTANY. 

from  flower  to  flower,  the  insect  is  almost  certain  to  transfer 
part  of  the  pollen  carried  off  from  one  flower  to  the  stigma  of 
another  of  the  same  kind,  thus  effecting  pollination. 

That  the  fertilization  of  a  flower  by  pollen  from  another  is 
beneficial  has  been  shown  by  many  careful  experiments  which 
show  that  nearly  always  —  at  least  in  flowers  where  there  are 
special  contrivances  for  cross-fertilization  —  the  number  of 
seeds  is  greater  and  the  quality  better  where  cross-fertilization 
has  taken  place,  than  where  the  flower  is  fertilized  by  its  own 
pollen.  From  these  experiments,  as  well  as  from  very  numer- 
ous studies  on  the  structure  of  the  flower  with  reference  to 
insect  aid  in  fertilization,  we  are  justified  in  the  conclusion 
that  all  bright-colored  flowers  are,  to  a  great  extent,  dependent 
upon  insect  aid  for  transferring  the  pollen  from  one  flower 
to  another,  and  that  many,  especially  those  with  tubular  or 
zygomorphic  (bilateral)  flowers  are  perfectly  incapable  of  self- 
fertilization.  In  a  few  cases  snails  have  been  known  to  be  the 
conveyers  of  pollen,  and  the  humming-birds  are  known  in  some 
cases,  as  for  instance  the  trumpet-creeper  (Fig.  121,  J.),  to 
take  the  place  of  insects.1 

At  first  sight  it  would  appear  that  most  flowers  are  especially 
adapted  for  self-fertilization;  but  in  fact,  although  stamens 
and  pistils  are  in  the  same  flower,  there  are  usually  effective 
preventives  for  avoiding  self-fertilization.  In  a  few  cases 
investigated,  it  has  been  found  that  the  pollen  from  the  flower 
will  not  germinate  upon  its  own  stigma,  and  in  others  it  seems 
to  act  injuriously.  One  of  the  commonest  means  of  avoiding 
self-fertilization  is  the  maturing  of  stamens  and  pistils  at  dif- 
ferent times.  Usually  the  stamens  ripen  first,  discharging 
the  pollen  and  withering  before  the  stigma  is  ready  to  receive 
it,  e.g.  willow-herb  (Fig.  113,  Z>),  campanula  (Fig.  123,  A,  D), 


1  In  a  number  of  plants  with  showy  flowers,  e.g.  violets,  jewel- weed, 
small,  inconspicuous  flowers  are  also  formed,  which  are  self-fertilizing. 
These  inconspicuous  flowers  are  called  "  cleistogamous." 


FERTILIZATION   OF  FLOWERS.  227 

and  pea;  in  the  two  latter,  the  pollen  is  often  shed  before 
the  flower  opens.  Not  so  frequently  the  stigmas  mature  first, 
as  in  the  plantain  (Fig.  121,  G). 

In  many  flowers,  the  stamens,  as  they  ripen,  move  so  as  to 
place  themselves  directly  before  the  entrance  to  the  nectary, 
where  they  are  necessarily  struck  by  any  insect  searching  for 
honey;  after  the  pollen  is  shed,  they  move  aside  or  bend 
downward,  and  their  place  is  taken  by  the  pistil,  so  that  an 
insect  which  has  come  from  a  younger  flower  will  strike  the 
part  of  the  body  previously  dusted  with  pollen  against  the 
stigma,  and  deposit  the  pollen  upon  it.  This  arrangement  is 
very  beautifully  seen  in  the  nasturtium  and  larkspur  (Fig. 
99,  J). 

The  tubular  flowers  of  the  Sympetalce  are  especially  adapted 
for  pollination  by  insects  with  long  tongues,  like  the  bees  and 
butterflies,  and  in  most  of  these  flowers  the  relative  position 
of  the  stamens  and  pistil  is  such  as  to  ensure  cross-fertiliza- 
tion, which  in  the  majority  of  them  appears  to  be  absolutely 
dependent  upon  insect  aid. 

The  great  orchid  family  is  well  known  on  account  of  the 
singular  form  and  brilliant  colors  of  the  flowers  which  have  no 
equals  in  these  respects  in  the  whole  vegetable  kingdom.  As 
might  be  expected,  there  are  numerous  contrivances  for  cross- 
fertilization  among  them,  some  of  which-  are  so  extraordinary 
as  to  be  scarcely  credible.  With  few  exceptions  the  pollen  is 
so  placed  as  to  render  its  removal  by  insects  necessary.  One' 
of  the  simpler  contrivances  is  readily  studied  in  the  little' 
spring-orchis  (Fig.  89)  or  one  of  the  Habenarias  (Fig.  90,  G). 
In  the  first,  the  two  pollen  masses  taper  below  where  each  is 
attached  to  a  viscid  disc  which  is  covered  by  a  delicate  mem- 
brane. These  discs  are  so  placed  that  when  an  insect  enters 
the  flower  and  thrusts  its  tongue  into  the  spur  of  the  flower, 
its  head  is  brought  against  the  membrane  covering  the  discs, 
rupturing  it  so  as  to  expose  the  disc  which  adheres  firmly  to 
the  head  or  tongue  of  the  insect,  the  substance  composing  the 


228  BOTANY. 

disc  hardening  like  cement  on  exposure  to  the  air.  As  the 
insect  withdraws  its  tongue,  one  or  both  of  the  pollen  masses 
are  dragged  out  and  carried  away.  The  action  of  the  insect 
may  be  imitated  by  thrusting  a  small  grass-stalk  or  some  simi- 
lar body  into  the  spur  of  the  flower,  when  on  withdrawing  it, 
the  two  pollen  masses  will  be  removed  from  the  flower.  If 
we  now  examine  these  carefully,  we  shall  see  that  they  change 
position,  being  nearly  upright  at  first,  but  quickly  bending 
downward  and  forward  (Fig.  89,  D  n,  m),  so  that  on  thrusting 
the  stem  into  another  flower  the  pollen  masses  strike  against 
the  sticky  stigmatic  surfaces,  and  a  part  of  the  pollen  is  left 
adhering  to  them. 

The  last  arrangement  that  will  be  mentioned  here  is  one  dis- 
covered by  Darwin  in  a  number  of  very  widely  separated  plants, 
and  to  which  he  gave  the  name  "heterostylism."  Examples 
of  this  are  the  primroses  (Primula),  loosestrife  (Lythrum), 
partridge-berry  (Mitchella),  pickerel-weed  (Pontederia)  (Fig. 
84,  /),  and  others.  In  these  there  are  two,  sometimes  three, 
sets  of  flowers  differing  very  much  in  the  relative  lengths 
of  stamens  and  pistil,  those  with  long  pistils  having  short 
stamens  and  'vice  versa.  When  an  insect  visits  a  flower  with 
short  stamens,  that  part  is  covered  with  pollen  which  in  the 
short-styled  (but  long-stamened)  flower  will  strike  the  stigma, 
as  the  pistil  in  one  flower  is  almost  exactly  of  the  length  of 
the  stamens  in  the  other  form.  In  such  flowers  as  have  three 
forms,  e.g.  Pontederia,  each  flower  has  two  different  lengths 
of  stamens,  both  differing  from  the  style  of  the  same  flower. 
Microscopic  examination  has  shown  that  there  is  great  varia- 
tion in  the  size  of  the  pollen  spores  in  these  plants,  the  large 
pollen  from  the  long  stamens  being  adapted  to  the  long  style 
of  the  proper  flower. 

It  will  be  found  that  the  character  of  the  color  of  the  flower 
is  related  to  the  insects  visiting  it.  Brilliantly  colored  flowers 
are  usually  visited  by  butterflies,  bees,  and  similar  day-flying 
insects.  Flowers  opening  at  night  are  usually  white  or  pale 


FERTILIZATION  OF  FLOWEES.  229 

yellow,  colors  best  seen  at  night,  and  in  addition  usually  are 
very  strongly  scented  so  as  to  attract  the  night-flying  moths 
which  usually  fertilize  them.  Sometimes  dull-colored  flowers, 
which  frequently  have  a  very  offensive  odor,  are  visited  by 
flies  and  other  carrion-loving  insects,  which  serve  to  convey 
pollen  to  them. 

Occasionally,  flowers  in  themselves  inconspicuous  are  sur- 
rounded by  showy  leaves  or  bracts  which  take  the  place  of 
the  petals  of  the  showier  flowers  in  attracting  insect  visitors. 
The  large  dogwood  (Fig.  110,  J),  the  calla,  and  Jack-in-the- 
pulpit  (Fig.  86,  A)  are  illustrations  of  this. 


CHAPTER   XXI. 

HISTOLOGICAL   METHODS. 

IN  the  more  exact  investigations  of  the  tissues,  it  is  often 
necessary  to  have  recourse  to  other  reagents  than  those  we 
have  used  hitherto,  in  order  to  bring  out  plainly  the  more 
obscure  points  of  structure.  This  is  especially  the  case  in 
studies  in  cell  division  in  the  higher  plants,  where  the  changes 
in  the  dividing  nucleus  are  very  complicated. 

For  studying  these  the  most  favorable  examples  for  ready  demonstra- 
tion are  found  in  the  final  division  of  the  pollen  spores,  especially  of  some 
monocotyledons.  An  extremely  good  subject  is  offered  by  the  common 
wild  onion  (Allium  Canadense),  which  flowers  about  the  last  of  May. 
The  buds,  which  are  generally  partially  replaced  by  small  bulbs,  are 
enclosed  hi  a  spathe  or  sheath  which  entirely  conceals  them.  Buds  two 
to  three  millimetres  in  length  should  be  selected,  and  these  opened  so  as 
to  expose  the  anthers.  The  latter  should  now  be  removed  to  a  slide,  and 
carefully  crushed  in  a  drop  of  dilute  acetic  acid  (one-half  acid  to  one-half 
distilled  water).  This  at  once  fixes  the  nuclei,  and  by  examining  with  a 
low  power,  we  can  determine  at  once  whether  or  not  we  have  the  right 
stages.  The  spore  mother  cells  are  recognizable  by  their  thick  trans- 
parent walls,  and  if  the  desired  dividing  stages  are  present,  a  drop  of 
staining  fluid  should  be  added  and  allowed  to  act  for  about  a  minute,  the 
preparation  being  covered  with  a  cover  glass.  After  the  stain  is  suffi- 
ciently deep,  it  should  be  carefully  withdrawn  with  blotting  paper,  and 
pure  water  run  under  the  cover  glass. 

The  best  stain  for  acetic  acid  preparations  is,  perhaps,  gentian  violet. 
This  is  an  aniline  dye  readily  soluble  in  water.  For  our  purpose,  however, 
it  is  best  to  make  a  concentrated,  alcoholic  solution  from  the  dry  powder, 
and  dilute  this  as  it  is  wanted.  A  drop  of  the  alcoholic  solution  is  diluted 
with  several  times  its  volume  of  weak  acetic  acid  (about  two  parts  of  dis- 
tilled water  to  one  of  the  acid),  and  a  drop  of  this  mixture  added  to  the 
preparation.  In  this  way  the  nucleus  alone  is  stained  and  is  rendered 
very  distinct,  appearing  of  a  beautiful  violet-blue  color. 

230 


HISTOLOGICAL  METHODS. 


231 


If  the  preparation  is  to  be  kept  permanently,  the  acid  must  all  be 
washed  out,  and  dilute  glycerine  run  under  the  cover  glass.  The  prepa- 
ration should  then  be  sealed  with  Canada  balsam  or  some  other  cement, 
but  previously  all  trace  of  glycerine  must  be  removed  from  the  slide  and 
upper  surface  of  the  cover  glass.  It  is  generally  best  to  gently  wipe  the 
edge  of  the  cover  glass  with  a  small  brush  moistened  with  alcohol  before 
applying  the  cement. 

If  the  spore  mother  cells  are  still  quite  young,  we  shall  find  the  nucleus 
(Fig.  127,  A,  n)  comparatively  small,  and  presenting  a  granular  appear- 
ance when  strongly 
magnified.  These 
granules,  which 
appear  isolated,  are 
really  parts  of  fila- 
ments or  segments, 
which  are  closely 
twisted  together, 
but  scarcely  visible 
in  the  resting  nu- 
cleus. On  one  side 
of  the  nucleus  may 
usually  be  seen  a 
large  nucleolus 
(called  here,  from 
its  lateral  position, 
paranucleus),  and 
the  whole  nucleus  is  sharply  separated  from  the  surrounding  protoplasm 
by  a  thin  but  evident  membrane. 

The  first  indication  of  the  approaching  division  of  the  nucleus  is  an 
evident  increase  in  size  (B),  and  at  the  same  time  the  colored  granules 
become  larger,  and  show  more  clearly  that  they  are  in  lines  indicating  the 
form  of  the  segments.  These  granules  next  become  more  or  less  conflu- 
ent, and  the  segments  become  very  evident,  appearing  as  deeply  stained, 
much-twisted  threads  filling  the  nuclear  cavity  (Fig.  127,  (7),  and  about 
this  time  the  nucleolus  disappears. 

The  next  step  is  the  disappearance  of  the  nuclear  membrane  so  that 
the  segments  lie  apparently  free  in  the  protoplasm  of  the  cell.  They 
arrange  themselves  in  a  flat  plate  in  the  middle  of  the  cell,  this  plate 
appearing,  when  seen  from  the  side,  as  a  band  running  across  the  middle 
of  the  cell.  (Fig.  127,  D,  shows  this  plate  as  seen  from  the  side,  E  seen 
from  above.) 


FIG.  127.  —  A,  pollen  mother  cell  of  the  wild  onion.  »?., 
nucleus.  B-F,  early  stages  in  the  division  of  the 
nucleus,  par.  nucleolus ;  acetic  acid,  gentian  violet, 
x  350. 


232 


BOTANY. 


About  the  time  the  nuclear  plate  is  complete,  delicate  lines  may  be 
detected  in  the  protoplasm  converging  at  two  points  on  opposite  sides  of 
the  cell,  and  forming  a  spindle-shaped  figure  with  the  nuclear  plate  occu- 
pying its  equator.  This  stage  (D)  is  known  as  the  "  nuclear  spindle. " 
The  segments  of  the  nuclear  plate  next  divide  lengthwise  into  two  similar 
daughter  segments  (F),  and  these  then  separate,  one  going  to  each  of  the 
new  nuclei.  This  stage  is  not  always  to  be  met  with,  as  it  seems  to  be 
rapidly  passed  over,  but  patient  search  will  generally  reveal  some  nuclei 
in  this  condition. 

Although  this  is  almost  impossible  to  demonstrate,  there  are  probably 

as  many  filaments  in  the  nuclear  spindle  as  there  are  segments  (in  this 

case  about  sixteen),  and  along  these  the  nuclear  segments  travel  slowly 

toward  the  two  poles  of  the  spindle  (Fig.  128,  A,  B).     As  the  two  sets 

IT    B  D  £  of    segments    sepa- 

rate'  they  are  seen 
to  be  connected  by 

very  numerous,  deli- 
cate  threads,  and 
about  the  time  the 
young  nuclei  reach 
the  poles  of  the  nu- 
clear spindle,  the 
first  trace  of  the  di- 
vision wall  appears 
in  the  form  of  iso- 
lated particles  (mi- 
crosomes),  which 
arise  first  as  thicken- 
ings of  these  threads 
in  the  middle  of  the 
cell,  and  appear  in  profile  as  a  line  of  small  granules  not  at  first  extend- 
ing across  the  cell,  but  later,  reaching  completely  across  it  (Fig.  128,  (7,  E). 
These  granules  constitute  the  young  cell  wall  or  "  cell  plate,"  and  finally 
coalesce  to  form  a  continuous  membrane  (Fig.  128,  F). 

The  two  daughter  nuclei  pass  through  the  same  changes,  but  in  reverse 
order  that  we  saw  in  the  mother  nucleus  previous  to  the  formation  of  the 
nuclear  plate,  and  by  the  time  the  partition  wall  is  complete  the  nuclei 
have  practically  the  same  structure  as  the  first  stages  we  examined  (Fig. 
128,  F).i 

1  The  division  is  repeated  in  the  same  way  in  each  cell  so  that  ultimately 
four  pollen  spores  are  formed  from  each  of  the  original  mother  cells. 


FIG.  128.  —  Later  stages  of  nuclear  divisions  in  the 
pollen  mother  cell  of  wild  onion,  x  350.  All  the 
figures  are  seen  from  the  side,  except  B  n,  which  is 
viewed  from  the  pole. 


H1STOLOGICAL  METHODS.  233 

This  complicated  process  of  nuclear  division  is  known  technically  as 
"  karyokinesis,"  and  is  found  throughout  the  higher  animals  as  well  as 
plants. 

The  simple  method  of  fixing  and  staining,  just  described, 
while  giving  excellent  results  in  many  cases,  is  not  always 
applicable,  nor  as  a  rule  are  the  permanent  preparations  so 
made  satisfactory.  For  permanent  preparations,  strong  alcohol 
(for  very  delicate  tissues,  absolute  alcohol,  when  procurable,  is 
best)  is  the  most  convenient  fixing  agent,  and  generally  very 
satisfactory.  Specimens  may  be  put  directly  into  the  alcohol, 
and  allowed  to  stay  two  or  three  days,  or  indefinitely  if  not 
wanted  immediately.  When  alcohol  does  not  give  good  results, 
specimens  fixed  with  chromic  or  picric  acid  may  generally  be 
used,  and  there  are  other  fixing  agents  which  will  not  be  described 
here,  as  they  will  hardly  be  used  by  any  except  the  professional 
botanist.  Chromic  acid  is  best  used  in  a  watery  solution  (five 
per  cent  chromic  acid,  ninety-five  per  cent  distilled  water). 
For  most  purposes  a  one  per  cent  solution  is  best ;  in  this  the 
objects  remain  from  three  or  four  to  twenty-four  hours,  de- 
pending on  size,  but  are  not  injured  by  remaining  longer. 
Picric  acid  is  used  as  a  saturated  solution  in  distilled  water, 
and  the  specimen  may  remain  for  about  the  same  length  of 
time  as  in  the  chromic  acid.  After  the  specimen  is  properly 
fixed  it  must  be  thoroughly  washed  in  several  waters,  allowing 
it  to  remain  in  the  last  for  twenty-four  hours  or  more  until  all 
trace  of  the  acid  has  been  removed,  otherwise  there  is  usually 
difficulty  in  staining. 

As  staining  agents  many  colors  are  used.  The  most  useful 
are  hsematoxylin,  carmine,  and  various  aniline  colors,  among 
which  may  be  mentioned,  besides  gentian  violet,  safranine, 
Bismarck  brown,  methyl  violet.  Hsematoxylin  and  carmine 
are  prepared  in  various  ways,  but  are  best  purchased  ready  for 
use,  all  dealers  in  microscopic  supplies  having  them  in  stock. 
The  aniline  colors  may  be  used  either  dissolved  in  alcohol  or 
water,  and  with  all,  the  best  stain,  especially  of  the  nucleus, 


234  BOTANY. 

is  obtained  by  using  a  very  dilute,  watery  solution,  and  allow- 
ing the  sections  to  remain  for  twenty-four  hours  or  so  in  the 
staining  mixture. 

Hsematoxylin  and  carmine  preparations  may  be  mounted 
either  in  glycerine  or  balsam.  (Canada  balsam  dissolved  in 
chloroform  is  the  ordinary  mounting  medium.)  In  using 
glycerine  it  is  sometimes  necessary  to  add  the  glycerine  grad- 
ually, allowing  the  water  to  slowly  evaporate,  as  otherwise 
the  specimens  will  sometimes  collapse  owing  to  the  too  rapid 
extraction  of  the  water  from  the  cells.  Aniline  colors,  as  a 
rule,  will  not  keep  in  glycerine,  the  color  spreading  and  finally 
fading  entirely,  so  that  with  most  of  them  the  specimens  must 
be  mounted  in  balsam. 

Glycerine  mounts  must  be  closed,  which  may  be  done  with 
Canada  balsam  as  already  described.  The  balsam  is  best  kept 
in  a  wide-mouthed  bottle,  specially  made  for  the  purpose,  which 
has  a  glass  cap  covering  the  neck,  and  contains  a  glass  rod  for 
applying  the  balsam. 

Before  mounting  in  balsam,  the  specimen  must  be  completely 
freed  from  water  by  means  of  absolute  alcohol.  (Sometimes 
care  must  be  taken  to  bring  it  gradually  into  the  alcohol  to 
avoid  collapsing.1)  If  an  aniline  stain  has  been  used,  it  will 
not  do  to  let  it  stay  more  than  a  minute  or  so  in  the  alcohol, 
as  the  latter  quickly  extracts  the  stain.  After  dehydrating, 
the  specimen  should  be  placed  on  a  clean  slide  in  a  drop  of 
clove  oil  (bergamot  or  origanum  oil  is  equally  good),  which 
renders  it  perfectly  transparent,  when  a  drop  of  balsam  should 
be  dropped  upon  it,  and  a  perfectly  clean  cover  glass  placed 
over  the  preparation.  The  chloroform  in  which  the  balsam  is 
dissolved  will  soon  evaporate,  leaving  the  object  embedded  in  a 
transparent  film  of  balsam  between  the  slide  and  cover  glass. 
No  further  treatment  is  necessary.  For  the  finer  details  of 

1  For  gradual  dehydrating,  the  specimens  may  be  placed  successively  in 
30  per  cent,  50  per  cent,  70  per  cent,  90  per  cent,  and  absolute  alcohol. 


HISTOLOGICAL  METHODS.  235 

nuclear  division  or  similar  studies,  balsam  mounts  are  usually 
preferable. 

It  is  sometimes  found  necessary  in  sectioning  very  small 
and  delicate  organs  to  embed  them  in  some  firm  substance 
which,  will  permit  sectioning,  but  these  processes  are  too  diffi- 
cult and  complicated  to  be  described  here. 


The  following  books  of  reference  may  be  recommended. 
This  list  is,  of  course,  not  exhaustive,  but  includes  those  works 
which  will  probably  be  of  most  value  to  the  general  student. 

1.  GOEBEL.     Outlines  of  Morphology  and  Classification. 

2.  SACHS.     Physiology  of  Plants. 

3.  DE  BARY.      Comparative  Anatomy  of  Ferns  and  Phane- 

rogams. 

4.  DE  BABY.     Morphology  and  Biology  of  Fungi,  Mycetozoa, 

and  Bacteria. 

These  four  works  are  translations  from  the  German, 
and  take  the  place  of  Sachs's  Text-book  of  Botany,  a  very 
admirable  work  published  first  about  twenty  years  ago, 
and  now  somewhat  antiquated.  Together  they  constitute 
a  fairly  exhaustive  treatise  on  general  botany.  —  New 
York,  McMillan  &  Co. 

5.  GRAY.     Structural  Botany.  —  New  York,  Ivison  &  Co. 

6.  GOODALE.     Physiological  Botany.  — New  York,  Ivison  &  Co. 

These  two  books  cover  somewhat  the  same  ground  as 
1  and  2,  but  are  much  less  exhaustive. 
5.  STRASBURGER.     Das  Botanische  Practicum.  —  Jena. 

Where  the  student  reads  German,  the  original  is  to  be 
preferred,  as  it  is  much  more  complete  than  the  transla- 
tions, which  are  made  from  an  abridgment  of  the  original 
work.  This  book  and  the  next  (7  and  8)  are  laboratory 
manuals,  and  are  largely  devoted  to  methods  of  work. 


236  BOTANY. 

7.  ARTHUR,  BARNES,  and  COULTER.     Plant  Dissection.  —  Holt 

&  Co.,  New  York. 

8.  WHITMAN.     Methods  in  Microscopic  Anatomy  and  Embry- 

ology.—  Casino  &  Co.,  Boston. 

For  identifying  plants  the  following  books  may  be  men- 
tioned :  — 

Green  algae  (exclusive  of  desmids,  bnt  including  Cyanopliy- 
cece  and  Volvocinece) . 

WOLLE.  Fresh-water  Algae  of  the  United  States.  —  Bethle- 
hem, Penn. 

Desmids.  WOLLE.  Desmids  of  the  United  States. — Bethle- 
hem, Penn. 

The  red  and  brown  algae  are  partially  described  in  FARLOW'S 
New  England  Algae.  Report  of  United  States  Fish  Com- 
mission, 1879.  —  Washington. 

The  Characece  are  being  described  by  Dr.  F.  F.  ALLEN  of  New 
York.  The  first  part  has  appeared. 

The  literature  of  the  fungi  is  much  scattered.  FARLOW  and 
TRELEASE  have  prepared  a  careful  index  of  the  American 
literature  on  the  subject. 

Mosses.  LESQUEREUX  and  JAMES.  Mosses  of  North  America. 
—  Boston,  Casino  &  Co. 

BARNES.  Key  to  the  Genera  of  Mosses.  —  Bull.  Purdue 
School  of  Science,  1886. 

Pteridophytes.  UNDERWOOD.  Our  Native  Ferns  and  their 
Allies.  —  Holt  &  Co.,  New  York. 

Spermaphytes.  GRAY.  Manual  of  the  Botany  of  the  North- 
ern United  States.  6th  edition,  1890.  This  also  includes 
the  ferns,  and  the  liverworts.  —  New  York,  Ivison  &  Co. 

COULTER.  Botany  of  the  Eocky  Mountains.  —  New  York, 
Ivison  &  Co. 

CHAPMAN.  Flora  of  the  Southern  United  States.  —  New 
York,  1883. 

WATSON.     Botany  of  California. 


INDEX. 


Acacia,  209. 

Acer,  -acex.   See  "Maple." 

Acetic  acid,  3,  59,  98,  138,  230. 

Achimenes,  218. 

Acorus.    See  "  Sweet-flag." 

Actinomorphic,  213. 

Adder-tongue,  116 ;  Fig.  70.    See  also 

"  Erythronium" 
Adiantum.    See  "  Maiden-hair." 
Adlumia.    See  "Mountain-fringe." 
^EsculinsB,  199. 

sEsculus.     See  "Buckeye,"  "Horse- 
chestnut." 
Aygref/atse,  222. 
Alcohol,  5,  31,  55,  83,  230,  233. 
Algae,  4,  21. 

green,  21. 

red,  21,  49. 

brown,  21.  41. 

Alga-fungi.    See  "Phy corny cetes." 
Alisma,  -cess.    See  "  Water-plantain." 
Alliu.m.    See  "  Wild  onion." 
Amaranth,  185. 

Amarantus,  -acese.   See  "Amaranth." 
Ama>ba,  1 ;  Fig.  2. 
Ampelidse.    See  "Vine." 
Ampelopsis.     See  "  Virginia  creeper." 
Anatomy,  3. 

gross,  Implements  for  study  of,  3. 

minute,  Implements  for  study  of, 

3,4. 

Anatropous,  151. 
Andreseacese,  99,  100. 
Androecium,  148. 
Andromeda,  211. 


Anemone,  185. 

Anyiocarpse,  84. 

Angiosperm,  129,  143, 145. 

Aniline  colors,  233. 

AnisocarpSB,  210,  213. 

Anonacese.    See  "  Custard-apple." 

Anther,  148, 175, 179. 

Antheridium,  27,  36,  39,  45,  51,  59,  68, 

89,  96,  106,  122. 

Anthoceros,  Anthocerotese,  91 ;  Fig.  57. 
Aphanocyclse,  185,  196. 
Aplectrum,  167 ;  Fig.  90. 
Apocynum,  -acese.    See ' '  Dog-bane." 
Apostasiese,  164. 
Apple,  145,  171,  206;  Fig.  114. 
Apricot,  207. 

Aquilegia.    See  "  Columbine." 
Aralia,  -acese.    See  "  Spikenard." 
Archegonium,  89,  97, 105,  122,  133, 140, 

144. 

Archicarp,  138, 145. 
Arcyria,  13 ;  Fig.  5. 
Arethusa,  Arethusese,  166 ;  Fig.  90. 
Argemone,  191. 
Aril,  189. 

Arissema,  78,  157 ;  Fig.  86. 
Aristolochia,  -acese,  224. 
Aroid,  Aroidese,  157. 
Arrow-grass,  167. 
Arrowhead,  167 ;  Fig.  91. 
Arrowroot,  163. 
Asarum.    See  "  Wild  ginger." 
Asclepias,  -dacese.    See ' '  Milk-weed." 
Ascobolus,  71-73 ;  Fig.  43. 
culture  of,  71. 


237 


238 


BOTANY. 


Ascobolus—  (Continued). 

spore  fruit,  71. 

archicarp,  71. 

spore  sacs,  72. 
Ascomycetes,  65,  66. 
Ascospore,  66. 
ASCIIS,  66,  69. 
Ash,  218 ;  Fig.  122. 
Asimina.    See  "  Papaw." 
Aspidium,  Fig.  70. 
Asplenium,  104 ;  Fig.  70. 
Aster,  224. 

Atropa.    See  "  Deadly  nightshade." 
Axil,  174. 

Azalea,  210;  Fig.  116. 
Azolla,  117 ;  Fig.  71. 

Bacteria,  15, 17, 19;  Fig.  8. 

Balsam,  Balsaminese,  198. 

Bamboo,  162. 

Bambusa.    See  "Bamboo." 

Banana,  163. 

Barberry,  17,  187 ;  Fig.  101. 

Bark.    See  "  Cortex." 

Basidiomycetes,  77. 

Basidium,  77,  80,  83. 

Basswood,  195 ;  Fig.  106. 

Bast.    See  "  Phloem." 

Batatas.    See  "  Sweet-potato." 

Batrachospermum,  53 ;  Fig.  31. 

Bean,  207,  208. 

Bear-grass.    See  "  Yucca." 

Bee,  227,  228. 

Beech,  183. 

Beech-drops,  218. 

Beet,  184. 

Beggar's-ticks,  215. 

Begonia,  3,  205. 

Bell-flower,  220,  226 ;  Fig.  123. 

Bellwort,  156. 

Berberis,  -idese.    See  ' '  Barberry.' ' 

Bergamot  oil,  234. 

Berry,  145, 156. 

Betulacese,  183. 

Bicornes,  210. 


Bignonia,  -acese,  218. 
Biology,  2. 
Birch,  183. 

Bird's-nest  fungus.    See  "  Cyathus." 
Bishop's  cap,  202 ;  Fig.  111. 
Bismarck  brown,  233. 
Bitter-sweet,  199 ;  Fig.  109. 
Black  alder,  199. 
Blackberry,  207. 

Black  fungi.    See  ' '  Pyrenomycetes.' ' 
Bladder-nut,  199 ;  Fig.  108. 
Bladder-weed,  33,  217;  Fig.  120. 
Bleeding-heart.    See  "Dicentra." 
Blood-root,  191 ;  Fig.  103. 
Blue-eyed  grass,  156. 
Blue-flag.    See  "7m." 
Blue-green  slime,  15. 
Blue  valerian.    See  "  Polemonium." 
Borage,  215. 

Borrayinese.    See  "Borage." 
Bordered  pits,  138. 
Botany  defined,  2. 
systematic,  3. 

Botrychium.   See  "Grape  fern." 
Box,  201. 

Bract,  199,  222,  229. 
Brasenia.    See  "Water-shield." 
Breathing  pore,  91,  99,  113,  130,  147, 

150,  177. 

BromeliacesB,  156. 
Bryophyte,  86. 
Buck-bean,  218. 
Buckeye,  171,  199. 
Buckthorn,  199. 
Buckwheat,  184. 
Budding,  64. 
BulbochsBte,  28 ;  Fig.  16. 
Bulb,  146,  153,  172, 
Bulrush,  161 ;  Fig.  87. 
Bundle-sheath,  110, 176. 
Burning-bush.    See  "  Spindle-tree." 
Bur-reed,  159 ;  Fig.  86. 
Buttercup,  181,  185 ;  Fig.  99. 
Butterfly,  227,  228. 
Button-bush,  223. 


INDEX. 


239 


Button  wood.    See  "  Sycamore." 
Buxus,  BuxacesB.    See  "  Box." 

Cabbage,  192. 

Cabombese,  190. 

Cactus,  Cactacese,  203 ;  Fig.  112. 

Csesalpinese,  210. 

Calcium,  2. 

Calla,  157,  229. 

Callithamnion,  50-52 ;  Fig.  29. 

general  structure,  51. 

tetraspores,  51. 

procarp,  51. 

antheridium,  51. 

spores,  52. 
Callitriche,    -chacese.      See    "Water 

star  wort." 

Calluna.    See  "  Heath." 
Calopogon,  166;  Fig.  91. 
Calycanthus,  -acese,  187 ;  Fig.  100. 
Calycerese,  223. 
Calyciflorse,  200. 
Calyx,  174,  182. 
Cambium,  137-138,  175. 
Campanula.    See  "  Bell-flower." 
Campanulacese,  220. 
CampanulinsB,  220. 
Canada  balsam,  230-234. 
Canada  thistle,  224 ;  Fig.  125. 
Canna,  -acess,  162,  163 ;  Fig.  88. 
Caper  family,  194. 
Capparis,  -idese.    See  "  Caper." 
Caprifoliacese,  223. 
Capsella.    See  "  Shepherd' s-purse." 
Caraway,  202. 
Carbon,  2,  95. 
Carbon-dioxides,  95. 
Cardinal-flower.    See  "  Lobelia." 
Carex,  161 ;  Fig.  87. 
Carmine,  25,  233. 
Carnation,  185. 
Carpel,  148,  154, 175,  179. 
Carpophyll.    See  "Carpel." 
Carpospore,  51-53. 
Carrot,  202. 


CaryophyllesB.    See  "  Pink." 

Caryophyllus.    See  "  Clove." 

Castalia,  189. 

Castor-bean,  200. 

Catalpa,  218. 

Cat-brier,  154. 

Catkin,  181. 

Catnip,  215. 

Cat-tail,  159. 

Cedar  apple,  Cedar  rust.    See  "  Gym- 

nosporangmm. 
CelastracesB,  199. 
Celastrus.    See  "Bitter-sweet." 
Celery,  3. 
Cell,  6. 

apical,  38,  96,  105, 115. 

division,  23,  31,  229. 

row,  8;  Fig.  3. 

mass,  8;  Fig.  4. 

sap,  6,  151. 
Cellulose,  3. 
Centaury,  219. 
Centrospermse,  183. 
Cephalanthus.     See  "Button-bush." 
Cerastium.    See  "  Chick-weed." 
(JeratophyUum.    See   "Horned  pond- 
weed." 

Cercis.    See  "  Red-bud." 
Chamserops.    See  "  Palmetto." 
Chara,  38-40 ;  Fig.  23. 

general  structure,  38. 

method  of  growth,  39. 

cortex,  39. 

non-sexual  reproduction,  39. 

oogonium,  39. 

antheridium,  39,  40. 

spermatozoids,  40. 

germination,  40. 
CharacesB,  21,  37,  40. 
CharesB,  40. 

Cheiranthus.    See  "Wall-flower." 
Chenopodium,    -acese.      See    "Goose- 
foot." 

Cherry,  15,  206;  Fig.  114. 
Chicory,  223. 


240 


BOTANY. 


Chick-weed,  185;  Fig.  98. 

Chimaphila.    See  "  Prince's  pine." 

Chionanthus.    See  "Fringe-tree." 

Chlorine,  2. 

Chlorococcum,  23 ;  Fig.  12. 

Chloroform,  234. 

Chloroplast,  22,  45. 

Chlorophyll,  15. 

Chlorophyll  body.  See  "  Chloroplast." 

Chlorophycess,  21. 

Chondrus.    See  "Irish  moss." 

Choripetalss,  181,  208. 

Chromic  acid,  25-35,  233. 

Chromoplast,  150. 

Cicinnobulus,  69;  Fig.  39. 

Cilium,  8. 

Cinquefoil,  206. 

Cistacese.    See  "  Rock-rose." 

Cistiflorsz,  192. 

Citron,  196. 

Citrus.     See  "  Orange,"  "  Lemon." 

Cladophora,  24,  25. 

structure  of  cells,  25. 

nuclei,  25. 

cell  division,  25. 

zoospores,  25. 
Classification,  3-9. 
Clavaria,  85;  Fig.  51. 
Claytonia.    See  ' '  Spring-beauty. ' ' 
Clematis,  185. 
Climbing  plants,  171. 
Closterium,  33;  Fig.  20. 
Clove,  205. 
Clove  oil,  234. 
Clover,  207. 
Club  moss,  116. 

larger,  116. 

smaller,  123-126;  Fig.  74. 
gross  anatomy,  125. 
spores,  126. 
prothallium,  126. 
systematic  position,  126. 
Cluster-cup,  78. 
Cocos.    See  "  Palm-coco,"  159. 
ColeochsBte,  28;  Fig.  17. 


Collateral  fibre-vascular  bundle,  135. 

Collema,  76 ;  Fig.  44. 

Columella,  55. 

Columbine,  186 ;  Fig.  99. 

Column,  165. 

Columiniferse,  195. 

CommelynesB,  157. 

Compositse,  223,  224. 

Compound  flower,  224. 

leaf,  159,  170. 
Conceptacle,  45. 
Cone,  131. 
Conferva,  26. 
Confervacese,  21,  24. 
Conidium,  68. 
Conifer,  129,  140,  141. 
Conifer se.    See  ' '  Conifer.' ' 
Conjugate,  22-29. 
Connective,  148. 

Conocephahis.  See  "Liverwort, giant. 
Contortss,  218. 
ConvolmilacesB,  213. 
Convolvulus.    See  "  Morning-glory." 
Coprinus,  82-84 ;  Fig.  48. 

general  structure,  82,  83. 

young  spore  fruit,  83. 

gills  basidia,  83. 

spores,  84. 
Coral  root,  167. 

Corallorhiza.    See  "  Coral  root." 
Coriander,  202. 
Corn,  160,  161. 

Cornus,  -acese.    See  "Dogwood." 
Corolla,  174,  182. 
Cortex,  39,  130. 
Corydalis,  192. 
Cotton,  195. 

Cotyledon,  134,  146,  180. 
Cowslip,  211. 
Coxcomb,  185. 
Crab-apple,  77,  80. 
Cranberry,  211. 
Crassulaceze,  203. 
Crane's-bill,  3,  196;  Fig.  107. 
Cress,  192. 


INDEX. 


241 


Croton,  200. 

Cruciferse.    See  "Mustard  family." 

Cruciflorss.    See  " Rhocadinse." 

Cucumber,  221. 

Cucumber-tree.    See  "Magnolia." 

Cucurbitacese.    See  "  Gourd." 

Cup  fungi  ("  Discomycetes  "),  71. 

Cupuliferse,  183. 

Curl,  66. 

Currant,  203. 

Cusciita.    See  "Dodder." 

Custard-apple,  186. 

CyanophycesB.        See     "  Blue  -  green 

slime." 

Cyathus,  84 ;  Fig.  50. 
Cycad,  -ese,  140. 
Cycas  revoluta,  141 ;  Fig.  71. 
Cyclamen,  212. 

Cynofjlossum.  See  "  Hound 's-tongue." 
Cyperacese.    See  "  Sedge." 
Cy perns,  161. 
Cypress,  142. 

Cypripedium.    See  "  Lady's-slipper." 
Cystopus.    See  also  "  White  rust." 

bliti,57;  Fig.  33. 

general  structure,  57. 

structure  of  filaments,  57. 

non-sexual  spores  (conidia) ,  57. 

germination  of  conidia,  58. 

resting  spores,  59. 

oogonium,  59. 

antheridium,  59. 

candidus,  60 ;  Fig.  34. 

Daisy,  223. 

Dandelion,  66,  223 ;  Fig.  125. 

Darlinytonia,  195. 

Datura.     See  "  Stramonium." 

Day  lily,  155. 

Deadly  nightshade,  215. 

Dead  nettle,  215 ;  Fig.  120. 

Delphinium.     See  "  Larkspur." 

Dermatogen,  176. 

Desmid,  33,  34;  Fig.  20. 

Devil's  apron.    See  "  Laminar ia." 


Dianthus.    See  "  Pink." 
Diatomacese,  41,  42 ;  Figs.  24,  25. 

structure,  42. 

movements,  42. 

reproduction,  42. 
Dicentra,  192;  Fig.  103. 
Dicotyledon,  145,  170,  181,  225. 
Digitalis.    See  "  Foxglove." 
Dioecious,  88. 

DionsRa.    See  "  Venus's  fly-trap." 
Dioscorese.    See  "Yam." 
Diascorea  villosa,  154. 
Diospyros.     See  "  Persimmon." 
Diospyrinse,  210. 
Dipsacus,  -acesB.    See  "  Teasel." 
Dirca.     See  "Moose-wood." 
Ditch-moss,  167 ;  Fig.  91. 
Dodder,  214. 

Dodecatheon.    See  "  Shooting-star." 
Dog-bane,  219;  Fig.  122. 
Dogwood,  202,  229;  Fig.  110. 
Drapernaldia,  26;  Fig.  14. 
Drosera,  -acess.    See  "  Sun-dew." 
Drupe.     See  "  Stone-fruit." 
Duck-weed,  159;  Fig.  86. 
Dutchman's  pipe.   See  "  Aristolochia." 

Earth  star.    See  "  Geaster." 
Ebenacese  (ebony),  212. 
Echinospermum.        See     "  Beggar's- 

ticks."    . 

Ectocarpvs,  45,  47 ;  Fig.  28. 
Eel-grass,  168,  169 ;  Fig.  91. 
Egg  apparatus,  144. 
Egg  cell,  27,  36,  39, 45,  90, 106,  133, 144. 
Egg-plant,  215. 
Eichler,  153. 
Elater,  91, 122. 
Elder,  224. 
Elteagnacese,  206. 
Elm,  183. 

Elodea.    See  "  Ditch-moss." 
Embryo,  90,  97,  107,  133,  149,  180, 
Embryology,  3. 
Embryo  sac,  143,  144,  151. 


242 


BOTANY. 


EnantioblastSB,  153,  156 ;  Fig.  85. 

Endosperm,  133, 146,  152. 

Entire  leaves,  170. 

EntomophthoresB,  57. 

Epacridex,  210. 

Epidermis,  91,  111,  112,  113,  122,  135, 

137,  150,  177. 

Epigsea.    See  "  Trailing  arbutus." 
Epilobium.    See  "  Willow-herb." 
Epiphegus.    See  "  Beech-drops." 
Epiphyte,  166. 

Equisetum,  -tinse.    See  "Horse-tail." 
Ergot,  76. 

Erica, -acex.   See  "Heath." 
Erysiphe,  70. 

Erythrssa.    See  "  Centaury." 
Erythronium,  146-152 ;  Fig.  81. 

leaf,  146. 

stem,  146. 

root,  146. 

gross  anatomy  of  stem,  147.- 

flower,  148. 

fruit  and  seed,  150. 

histology  of  stem,  150. 
of  leaf,  150. 
of  flower,  151. 
of  ovule  and  seed,  151,  152. 
Eschscholtzia,  191. 
Eucalyptus,  206. 
Eucyclse,  196,  200. 
Eudorina,  20. 
Euglena,  11,  19 ;  Fig.  9. 
Euonymus.    See  "  Spindle-tree." 
Euphorbia,  199 ;  Fig.  109. 
Eurotium,  70;  Fig.  42. 
Evening  primrose,  206. 
Exoascus,  66. 

Fagopyrum.    See  "  Buckwheat." 
Feather-veined.  See  "  Pinnate-veined." 
Fern,  5, 102,  104,  116. 

flowering,  118;  Fig.  70. 

lady,  104;  Fig.  70. 

maiden-hair.     See    "  Maiden-hair 
fern." 


Fern —  (Continued). 

ostrich.    See  "  Ostrich-fern." 

sensitive,  104. 

true,  117. 

water.    See  "  Water-fern." 
Fertilization,  225. 
Fibre,  124,  175, 177. 
Fibro-vascular  bundle,   107,   110,  121, 

123,  135,  136,  147,  150,  159,  174. 
Fig,  183. 

Figwort,  215,  216;  Fig.  120. 
Filament  (of  stamen),  148,  174. 
Filices.    See  "  True  ferns." 
Filicinese.    See  "  Fern." 
Fir,  142. 
Fission,  23. 
Flagellata,  19. 
Flagellum,  19. 
Flax,  197 ;  Fig.  107. 
Flies,  229. 
Flower,  128, 131. 

Flowering-plant.  See ' '  Spermaphyte." 
Forget-me-not,  215. 
Four-o'clock,  183. 
Foxglove,  217. 
Frangulinse,  199. 
Fraxinus.    See  "Ash." 
Fringe-tree,  218 ;  Fig.  122. 
Fruit,  145. 
Fucacese,  43. 
Fuchsia,  201. 
Fucus,  42-46. 

vesiculosus,  43 ;  Figs.  26,  27.- 

general  structure,  43,  44. 

conceptacles,  44. 

collecting  plants,  44. 

cells,  44. 

chloroplasts,  44. 

oogonium,  45. 

platycarpus,  45. 

antheridium,  45,  46. 

fertilization,  46. 

germination,  46. 

Fumariacese.    See  "  Fumitory." 
Fumitory,  192. 


INDEX. 


243 


Funaria,  93-99 ;  Figs.  58-62. 

gross  anatomy,  93,  94. 

protonema,  93. 

"flower,"  94. 

structure  of  leaf,  94. 

chloroplasts,  division  of,  95. 

formation  of  starch  in  chloroplasts, 
95. 

structure  of  stem,  96. 

root  hairs,  96. 

buds,  96. 

antheridium  spermatozoids,  96,  97. 

archegonium,  97. 

embryo,  98. 

capsule  and  spores,  98,  99. 

germination  of  spores,  99. 
Fungi,  culture  of,  5,  54. 

true.    See  "  My corny cetes." 

alga.    See  "  Phy  corny  cetes." 
Funiculus,  151,  175. 
Funkia.    See  "Day  lily." 

Galium,223;  Fig.  124. 

Gamopetalse.    See  "  Sympetalas." 

Gaultheria.    See  "  Wintergreen." 

Gaylussacia.    See  "  Huckleberry." 

Geaster,  84 ;  Fig.  49. 

Gentian,  218 ;  Fig.  122. 

Gentian  violet,  4,  138,  231. 

Gentiana,  -acese.    See  "Gentian." 

Geranium,  -acese,  3,  171,  196;  Fig.  107. 

Gerardia,  217. 

Germ  cell.    See  "  Egg  cell." 

Gesneracese,  218. 

Ghost  flower.    See  "  Indian-pipe." 

Gill,  83. 

Ginger,  163. 

Gingko,  142 ;  Fig.  78. 

Gledi  tschia.    See  ' '  Honey  locust.' ' 

Gloxinia,  218. 

Glumacese,  153, 160;  Fig.  87. 

Glume,  162. 

Glycerine,  4,  51,  55,  59,  67,  83,  98,  224, 

231,  233. 
Gnetacese.    See  ' '  Joint  fir.' ' 


Golden-rod,  224. 

Gonium,  20. 

Gooseberry,  203;  Fig.  111. 

Goose-foot,  184;  Fig.  98. 

Gossypium.    See  "Cotton." 

Gourd,  221. 

Graminese.    See  "  Grass." 

Grape,  171,  199;  Fig.  109. 

Grape  fern,  116 ;  Fig.  70. 

Graphis,  75 ;  Fig.  45. 

Grass,  161,  225 ;  Fig.  87. 

Gray  moss.    See  "  Tillandsia." 

Green-brier,  154. 

Green-felt.    See  "  Vaucheria" 

Green  monad,  12, 19. 

Green  slime,  21,  22;  Fig.  11. 

Ground  pine,  123 ;  Fig.  73. 

Ground  tissue,  110,   111,  113,  124,  137, 

177,  178. 
Gruinales,  196. 
Guard  cell,  113,  135,  150. 
Gulf  weed.    See  "  Sargassum." 
Gum.    See  "  Eucalyptus" 
Gymnocarpse,  84. 
Gymnosperm,  129, 141. 
Gymnosporanyiitm,  79-81 ;  Fig.  47. 

cedar  apples,  79. 

spores,  80. 

Gynandrse,  153,  164. 
Gynoecium,  148,  167. 
Gynostemium.  See  "Column." 

Habenaria,  166,  227;  Fig.  90. 

Haematoxylin,  233. 

Hair,  8,  177. 

HaloragidacesB,  206. 

Hazel,  182,  183,  225 ;  Fig.  97. 

Head,  181. 

Heath,  211. 

Helobise,  153,  167. 

Hemerocallis.    See  "Day  lily." 

Hetni-angiocarpss,  84. 

Hemlock,  142 ;  Fig.  78. 

Hemp,  183. 

HepaticsB.    See  "  Liverwort." 


244 


BOTANY. 


Hermaphrodite,  199. 

Heterocyst,  17. 

Heterostylism,  228. 

Hibiscus,  195. 

Hickory,  170,  183. 

Holly,  199. 

Hollyhock,  195. 

Honey  locust,  209. 

Honeysuckle,  170,  172,  181,  223;   Fig. 

124. 

Hop,  171,  181;  Fig.  97. 
Horned  pond-weed,  224. 
Horse-chestnut,  170, 199. 
Horse-tail,  116-120. 

field,  120-122;  Fig.  72. 

stems  and  tubers,  120. 

fertile  branches,  120. 

leaves,  121. 

cone,  121. 

stem,  121. 

sporangia  and  spores,  121. 

sterile  branches,  121. 

histology  of  stem,  121. 
of  sporangia,  122. 

spores,  122. 

germination,  prothallium,  122. 
Hound 's-tongue,  215;  Fig.  119. 
Houstonia,  223;  Fig.  124. 
Hoya.     See  "  Wax-plant.!' 
Huckleberry,  181,  211;  Fig.  116. 
Humming-bird,  226. 
Hyacinth,  146. 
Hydnum,  84 ;  Fig.  51. 
Hydrangea,  -yese,  202;  Fig.  111. 
Hydrocharidese,  167. 
Hydrogen,  2,  95. 
Hydropeltidinse,  189. 
Hydrophyllum,  -acess.     See  "Water- 
leaf." 

Hypericnm,  -acese.     See   "St.  John's- 
wort." 


Ilex.    See  "  Holly." 
Impatiens.    See  "Jewel-weed,' 
sam." 


Bal- 


India-rubber,  200. 

Indian-pipe,  144,  210 ;  Fig.  79. 

Indian  turnip.    See  "Arissema." 

Indusium,  118. 

Inflorescence,  157. 

Integument,  133,  144,  151,  180. 

Intercellular  space,  124,  135,  150. 

Internode,  39. 

Iodine,  4,  22,  31. 

Ipomcea,  213. 

Iridacese,  156. 

Iris,  154,  156;  Fig.  84. 

Irish  moss,  49. 

IsocarpsB,  210,  212. 

Isoetes.    See  "Quill- wort." 

luliflora,  181. 

Ivy,  202. 

Jack-in-the-pulpit.    See  "Arissema." 

Jasmine,  218. 

Jeffersonia.    See  "  Twin-leaf." 

Jewel-weed,  197 ;  Fig.  107. 

Joint  fir,  140,  142. 

Juncac/inese,  167. 

Juncus.    See  "  Rush." 

Jungermanniacese,  92 ;  Fig.  57. 

Kalmia.    See  "  Mountain  laurel." 

Karyokinesis,  233. 

Keel,  208. 

Kelp.    See  "Laminaria." 

giant.    See  "Macrocystis." 
Knotgrass.    See  "Polyyonum." 

Labellum.    See  "  Lip." 

Labiatse.    See  "  Mint." 

Labiatiflorae,  215. 

Lady's-slipper,  164, 166,  198;  Fig.  90. 

Lamella,  83. 

Laminaria,  45,  47 ;  Fig.  28. 

Lamium.     See  "  Dead  nettle." 

Larch.    See  "  Tamarack." 

Larix.    See  "  Tamarack." 

Larkspur,  186,  227;  Fig.  99. 

Latex,  191. 


INDEX. 


245 


Laurel,  188. 

Laurinese.    See  "  Laurel." 

Lavender,  215. 

Leaf-green.    See  "  Chlorophyll." 

Leaf  tendril,  171. 

Leaf  thorn,  172. 

Leyuminosse,  207. 

Lemanea,  53 ;  Fig.  31. 

Lemna.    See  "Duck-weed." 

Lemon,  198. 

LentibulariaccsB,  217. 

Lettuce,  223. 

Lichenes,  73 ;  Figs.  44,  45. 

Ligula,  127. 

Ligulatse,  125. 

Lilac,  170,  181,  218. 

LiliacesB,  155. 

Liliiflorse,  153,  155 ;  Fig.  83. 

Lilium.    See  "Lily." 

Lily,  146, 155. 

Lily-of-the-valley,  155. 

Lime.    See  "  Linden." 

Linden,  195 ;  Fig.  106. 

Linear,  159. 

Linum,  -acese.    See  "Flax." 

Lip,  165. 

Liriodendron.    See  "  Tulip-tree." 

Lithospermum.    See  "  Puccoon." 

Liverwort,  86. 

classification  of,  91. 

horned.    See  " Anthocerotese." 

giant,  91 ;  Fig.  57. 
Lizard-tail,  181,  183;  Fig.  97. 
Lobelia,  -acese,  221;  Fig.  123. 
Loganiese,  219. 

Lonicera.    See  "  Honeysuckle." 
Loosestrife.    See  "Ly thrum." 

swamp.    See  "Nessea." 
Lotus,    See  "Nelumbo." 
Lychnis,  185. 
Lycoperdon,  84 ;  Fig.  49. 
Lycopersicum.    See  "Tomato." 
Lycopodiacese.    See  "Ground  pine." 
Lycopodinse.    See  "  Club  moss." 
Lycopodium,  123. 


Lycopodium  —  (Continued) . 

dendroideum,  123,  124;  Fig.  73. 

stem  and  leaves,  123. 

cones  and  sporangia,  123. 

gross  anatomy,  123. 

histology,  124. 

spores,  124. 

Lysimachia.     See  "  Moneywort." 
Lythrum,  -acese,  206,  228. 

Mace,  189. 
Macrocystis,  48. 
Macrospore,  126,  127,  128, 143. 
Madotheca,  86-90;  Figs.  52-56. 

gross  anatomy,  86-88. 

male  and  female  plants,  87,  88. 

histology  of  leaf  and  stem,  88. 

antheridium,  88,  89. 

archegonium,  89,  90. 

embryo,  90. 

spores  and  elaters,  90. 
Magnesium,  2. 
Magnolia,  -acese,  186. 
Maiden-hair  fern,  109-115 ;  Figs.  67-69. 

general  structure,  109. 

gross  anatomy  of  stem,  110. 

histology  of  stem,  110,  111. 

gross  anatomy  of  leaf,  111. 

histology  of  leaf,  111,  112. 

sporangia,  113,  114. 

root,  114,  115. 

apical  growth  of  root,  115. 
Mallow,  171,  195 ;  Fig.  106. 
Malva,  -acese.    See  "  Mallow." 
Mamillaria,  Fig.  112. 
Mandrake.    See  "May-apple." 
Maple,  199;  Fig.  108. 
Maranta.    See  "  Arrow-root." 
Marattiacese.     See  "  Ringless  ferns." 
Marchantia,  91;  Fig.  57. 

breathing-pores,  91. 

sexual  organs,  91. 

buds,  91. 

Marchantiacese,  91. 
Marsilia,  118;  Fig.  71. 


246 


BOTANY. 


Marty nia,  218. 

Matthiola.    See  "  Stock." 

May-apple,  187;  Fig.  101. 

May-weed,  223;  Fig.  125. 

Medeola,  155;  Fig.  83. 

Medullary  ray,  130, 137. 

Mdampsora,  81. 

MelastomacesB,  206. 

Melon,  221. 

Memspernum,  -ess.  See  "  Moon-seed." 

Menyanthes.    See  "  Buck-bean." 

Mesocarpus,  33,  Fig.  19. 

Mesophyll,  135. 

Methyl-violet,  4,  233. 

Micropyle,  180. 

Microsome,  231. 

Microspore,  126,  128,  131,  138. 

Mignonette,  192;  Fig.  104. 

Mildew.     See  "  Peronospora,"  "  Phy- 
tophthora,"  "Perisporiacese." 

Milk-weed,  220;  Fig.  122. 

Milk-wort,  199. 

Mimosa.    See  "  Sensitive-plant." 

Mimosacese,  209,  210. 

Mimulus,  217. 

Mint,  181,  215. 

Mirabilis.    See  "Four-o'clock." 

Mistletoe,  224. 

Mitella.    See  "  Bishop's  cap." 

Mitchella.    See  "  Partridge-berry." 

Mitre-wort.    See  "  Bishop's  cap." 

Mock-orange.    See  "Syringa." 

Money-wort,  212;  Fig.  117. 

Monocotyledon,  146,  153,  225,  229. 

Monotropa.  See  "  Indian-pipe,"  "  Pine- 
sap." 

Monotropese,  210. 

Moon-seed,  188  ?  Fig.  101. 

Moose-wood,  206;  Fig.  113. 

Morchella.    See  "  Morel." 

Morel,  73. 

Morning-glory,  171,  213 ;  Fig.  118. 

Morphology,  3. 

Moss,  5,  86. 
true,  93. 


Moss  —  (Continued) . 

common.    See  "  Bryacese." 
peat.    See  "  Sphagnacese." 

Moth,  229. 

Mould,  black.    See  "  Mucorini." 
blue.    See  "  Penicillium." 
herbarium.    See  "  Eurotium." 
insect.    See  "  Entomophthorese." 
water.     See  "  Saproleynia.'" 

Mountain-fringe,  192. 

Mountain-laurel,  210;  Fig.  116. 

Mucor,  55. 

mucedo,  56 ;  Fig.  32. 

Mucor  stolonifer,  55-56. 
general  structure,  55. 
structure  of  filaments,  55. 
spore  cases,  55. 
sexual  spores,  56. 

Mucorini,  54. 

Mulberry,  183. 

Mullein,  217 ;  Fig.  120. 

Musa,  -acex.    See  "  Banana." 

Musci.    See  "  True  mosses." 

Mushroom,  82. 

Mustard,  192. 

Mycomycetes.    See  "True  fungi." 

Myosotis.    See  "  Forget-me-not." 

Myristica,  -inese.    See  "  Nutmeg." 

Myrtiflorse,  205. 

Myrtle,  205,206. 

Myrtus.    See  "  Myrtle." 

Myxomycetes.    See  "  Slime-mould." 

Naias.    See  ' '  Pond-weed . ' ' 

Naiadese,  159. 

Narcissus,  146. 

Nasturtium,  197,  227. 

Navicula,  42;  Fig.  24. 

Nectar,  225. 

Nectary,  186. 

Nelumbo,  189,  190;  Fig.  101. 

Nelumbiese,  190. 

Nemophila,  214. 

Nepenthes,  -ese.    See  "  Pitcher  plant." 

Ness&a,  206. 


INDEX. 


247 


Nettle.    See  "  Urticinss." 

Nicotiana.    See  "  Tobacco." 

Night-blooming  cereus,  204. 

Nightshade,  215;  Fig.  119. 

ffitella,  40. 

Nitellese,  40. 

Node,  39. 

Nucleus,  7,  31,  231. 

Nuclear  division,  7,  31,  231;  Figs.  127, 

128. 

Nucleolus,  7,  231. 
Nutmeg,  188. 
Nyctayinese,  183. 
Nymphaea,  189 ;  Fig.  101. 
Nymphseacese,  190. 

Oak,  183,  225 ;  Fig.  97. 
(Edogonium,  26-28 ;  Fig.  16. 

reproduction,  27. 

fertilization,  28. 

resting  spores,  28. 

(Enothera.    See  "  Evening  primrose." 
Oil-channel,  202. 
OleacesB.    See  "  Olive." 
Oleander,  219. 
Olive,  218. 
Onagracese,  206. 
Onoclea,  104;  Fig.  70. 
Oogonium,  27,  36,  39,  45,  59,  62. 
Oophyte,  109. 

Opium  —  opium  poppy,  191. 
OphioylossesB.    See  "Adder-tongue." 
Ophioglossum,  116. 
Opuntia.    See  "  Prickly  pear." 
Opuntiess,  203. 
Orange,  198. 

Orchid,  164, 166,  227;  Figs.  89,  90. 
OrchidesB,  164. 
Orchis,  227;  Fig.  89. 
Organic  bodies,  1. 
Origanum  oil,  234. 
Oscillaria,  15, 16;  Fig.  6. 

movements,  15. 

color,  16. 

structure  and  reproduction,  16. 


Osmunda.    See  "  Flowering-fern." 
Ostrich-fern,  104-109. 

germination  of  spores,  104. 

prothallium,  104, 105. 

archegonium,  105,  106. 

antheridium    and    spermatozoids, 
106. 

fertilization,  107. 

embryo  and  young  plant,  107,  108. 

comparison  with  sporogonium  of 

bryophytes,  109. 
Ovary,  129,  148, 156,  202. 
Ovule,  129,  131, 144,  148, 151,  179. 
Oxalis.    See  "  Wood-sorrel." 
Oxydendrum,  211;  Fig.  116. 
Oxygen,  2,  95. 

Palea,  161. 

Palisade  parenchyma,  178. 

Palm,  157. 

date,  159. 

coco,  159. 

Palmss.    See  "Palm." 
Palmate,  171. 
Palmetto,  159. 
Pandanex,  159. 
Papaveracese.    See  "Poppy." 
Papaw,  186 ;  Fig.  100. 
PapilionacesB,  208. 
Pappus,  223. 
Papyrus,  161. 
Paranucleus,  231. 
Parasite,  54. 

Parenchyma.    See  "  Soft  tissue." 
Parmelia,  73,  75 ;  Fig.  44. 
Partridge-berry,  223,  228. 
Passiflora.    See  "  Passion-flower." 
Passiflormse,  205. 
Passion-flower,  204;  Fig.  112. 
Pea,  207,  208;  Fig.  115. 
Peach,  206. 
Pear,  206. 

Pediastrum,  23 ;  Fig.  11. 
Pelargonium,  197. 
Peltate,  190. 


248 


BOTANY. 


Peltigera,  75 ;  Fig.  45. 
Penicillium,  71 ;  Fig.  42. 
Pepper,  183. 

Perianth.    See  "  Perigone." 
Periblem,  170. 
Perigone,  143,  148,  151, 170. 
Perisperm,  163. 
Perisporiacese,  66. 
Periwinkle,  219. 
Peronospora,  60;  Fig.  35. 
PeronosporesB,  57. 
Persimmon,  212;  Fig.  117. 
Petal,  148,  174, 179. 
Petiole,  173. 
Petunia,  215;  Fig.  119. 
Peziza,  73 ;  Fig.  43. 
Phacelia,  214. 

Phseophycese.    See  "Brown  algae." 
Phaenogam.    See  "  Spermaphyte." 
Phascum,  -acese,  99,  101;  Fig.  65. 
Philadelphus.    See  "  Syringa." 
Phloem,  110, 124,  135,  137,  150, 173, 176. 
Phlox,  214;  Fig.  118. 
Phcenix    dactylifera.       See    "  Date- 
palm." 

Phosphorus,  2. 
Phragmidium,  81 ;  Fig.  47. 
Physarum,  14. 
Physianthus,  220. 
Physiology,  3. 

Phytolacca, -acese.    See  "Poke-weed." 
Phytophthora,  60. 
Pickerel-weed,  156,  228;  Fig.  84. 
Picric  acid,  156,  233. 
Pig- weed.    See  "  Amaranth." 
Pine,  9, 10,  129,  142. 
Pine-apple,  156. 
Pine-sap,  210;  Fig.  116. 
Plngutcula,  218. 
Pink,  181,185;  Fig.  97. 
Pink-root,  218;  Fig.  122. 
Pinnate  (leaf),  159. 

veined,  171. 

Pinnularia,  42 ;  Fig.  24. 
Pinus  sylvestris.    See  "  Scotch  pine." 


Piper.    See  "Pepper." 

Piperinese,  183. 

Pistil,  143,  145,  174. 

Pitcher-plant,  194,  195 ;  Fig.  105. 

Pith,  130,  174, 177. 

Placenta,  148,  179. 

Plane,  183. 

Plantago,  -inese.    See  "  Plantain." 

Plantain,  223,  225 ;  Fig.  121. 

Plasmodium,  12. 

Platanese.    See  "  Plane." 

Platanus.    See  "  Sycamore." 

Plerome,  176. 

Plum,  207. 

Plumbago,  -inese,  212. 

Pod,  156. 

Podophyllum.    See  "  May-apple." 

Podosphsera,  66-70;  Fig.  39. 

general  structure,  66. 

structure  of  filaments,  68. 

suckers,  68. 

conidia,  68. 

sexual  organs,  68. 

spore  fruit,  68,  69. 

spore  sac,  69. 
Pogonia,  166. 
Poinsettia,  199. 
Poison-dogwood,  198. 
Poison-hemlock,  202. 
Poison-ivy,  171,  198. 
Poke-weed,  185;  Fig.  97. 
Polemonium,  -acese,  214 ;  Fig.  118. 
Pollinium,  165. 
Polycarpse,  185. 

Poly  gala,  -acess.    See  "  Milk- wort." 
Polygonatum.    See  "Solomon's Seal. 
Polygonurn,  -acese,  184;  Fig.  98. 
Polysiphonta,  52;  Fig.  29. 
Pomegranate,  206. 
Pond-scum,  22,  29,  30. 
Pond-weed,  159;  Fig.  86. 
Pontederia.    See  "  Pickerel-weed." 
Poplar,  181, 183. 
Poppy,  191. 
Portulaca,  -acex.    See  "  Purslane." 


INDEX. 


249 


Potash  (caustic),  4, 5,  59,  67.  75,  97, 106, 

111,  151,  176,  179,  180. 
Potassium,  2. 
Potato,  215. 

Potato-fungus.    See  "  Phytophthora." 
Potentilla.     See  "  Cinque-foil." 
Potomogeton.    See  "  Pond-weed." 
Prickly-ash,  198. 

Prickly  fungus.    See  " Hydnum." 
Prickly -pear,  204. 
Prickly-poppy.    See  "  Aryemone." 
Primrose,  211. 

Primula,  -acese.    See  "  Primrose." 
Prince's-pine,  210;  Fig.  116. 
Procarp,  51. 
Proteacese,  205. 
Prothallium,  102,  103, 114,  122, 125, 133, 

144,  177. 

Protococcus,  -acese,  22,  74;  Fig.  11. 
Protophyte,  11. 
Protoplasm,  7. 

movements  of,  7. 
Pteridophyte,  102,  153. 
Puccinia,     81  ;    Fig.   47.      See    also 

"  Wheat-rust." 
Puccoon,  215. 

Puff-ball.    See  "  Lycoperdon." 
Purslane,  185. 

Putty-root.    See  "Aplectrum." 
Pyrenoid,  25,  31. 
Pyrenomycetes,  76. 
Pyrola,  -acese,  210. 

Quince,  170. 

Quill-wort,  125,  126 ;  Fig.  74. 

Raceme,  174. 

Radial  fibro-vascular  bundles,  138, 
176. 

Radish,  192. 

Ranunculus,  -acese.  See  "Butter- 
cup." 

Raspberry,  207. 

Ray-flower,  223. 

Receptacle,  167,  207,  223. 


Receptive  spot,  106. 

Red  alga,  21,  49,  52,  53;  Figs.  29-31. 

Red-bud,  209;  Fig.  115. 

Red  cedar,  79, 131, 141 ;  Fig.  78. 

Red-wood,  142. 

Reference-books,  235-236. 

Reseda,  -acese.    See  "  Mignonette." 

Resin,  130. 

Resin-duct,  130,  135,  137. 

Resting-spore,  28,  32,  37,  57. 

Rheumatism-root.    See  "  Twin-leaf." 

Rhexia,  206. 

RJdzocarpese.    See  "  Water-fern." 

Rhizoid.    See  "  Root-hair." 

Rhizome.    See  "  Root-stock." 

Rhododendron,  210 ;  Fig.  116. 

Rhodophycese.    See  "  Red  algae." 

Rhodoracese,  211. 

Rh<j>adinse,  190. 

Rhus.    See  "  Sumach." 

cotinus.    See  "  Smoke-tree." 
toxiocodendron.  See" Poison-ivy." 
venenatct.  See ' '  Poison-dogwood.' ' 

Ribes,  -iese,  203;  Fig.  111. 

Ricciacese,  91 ;  Fig.  57. 

Richardia.    See  "Calla." 

Ricinus.    See  "  Castor-bean." 

Ringless-fern,  116. 

Rock-rose,  195. 

Rock-weed.    See  "  Fucus." 

Root,  102,  104,  114, 173. 

Root-cap,  115,  175. 

Root-hair,  38,  87,  91,  96,  104,  135. 

Root-stock,  154,  172. 

Rosa,  -acese.    See  "  Rose." 

Rose,  181,  206 ;  Fig.  114. 

Rosiflorse,  206. 

Rubiacese,  223. 

Rush,  154,  225 ;  Fig.  83. 

Rust,  white.    See  "  Cystopus." 
red.    See  "  Urediness." 
black.    See  "  Urediness." 

Sabal.    See  "  Palmetto." 
Sabbatia.    See  "  Centaury." 


250 


BOTANY. 


Saccharomycetes.    See  "  Yeast." 

Sac  fungi.    See  "  Ascomycetes." 

Safranine,  233. 

Sage,  215 ;  Fig.  120. 

SalicinesB,  183. 

Salix.    See  "  Willow." 

Salvinia,  118. 

Sambucus.    See  "Elder." 

Sanyuinaria.    See  "  Blood-root." 

Sapindacess,  199. 

Saprolegnia,  -acese,  60-62;  Fig.  36. 

zoospores,  62. 

resting  spores,  62. 

antheridium,  62. 
Sargassum,  48;  Fig.  28. 
Sarracenia,    -acese.      See    "  Pitcher- 
plant." 

Sassafras,  188. 

Saururus.    See  "  Lizard-tail." 
Saxifrage,  202. 
Saxifraginse,  202. 
Scabiosa.    See  "  Scabious." 
Scabious,  224. 
Scalariform,  110. 
Scale-leaves,  170. 
Scenedesmus,  24;  Fig.  11. 
Schizomycetes.    See  "  Bacteria." 
Schizophytes,  12,  14. 
Schlerenchyma.     See  "Stony  tissue." 
Schrankia.    See  "  Sensitive-brier." 
Scilla,  151. 

Scirpus.    See  "  Bulrush." 
ScitaminesB,  153,  162. 
Scotch  pine,  129-140;  Figs.  75-77. 

stems  and  branches,  129. 

leaves,  129, 130. 

gross  anatomy  of  stem,  130. 

growth-rings,  130. 

roots,  131. 

sporangia,  131. 

cones,  132. 

macrospores  and  prothallium,  133. 

ripe  cone  and  seeds,  133. 

germination,  134. 

young  plant,  134. 


Scotch  pine —  (Continued), 
histology  of  leaf,  135. 
of  stem,  136-138. 
of  root,  138. 
microsporangium       and       pollen 

spores,  138,  139. 
archegonium,  140. 
fertilization,  140. 
Scouring-rush,  122. 

Scrophularia,  -ineas.    See  "  Fig-wort." 
Sea-lettuce,  26;  Fig.  15. 
Sea-rosemary,  212. 
Sea-weed     (brown).        See     "  Brown 


(red).    See  "  Red  algae." 
Sedge,  161 ;  Fig.  87. 
Scdum.    See  "  Stone-crop." 
Seed,  128,  133,  145,  150. 
Seed-plant.    See  "  Spermaphyte." 
Selaginella,  -ex.    See  "Smaller  club- 
moss." 

Sensitive-brier,  209 ;  Fig.  115. 
Sensitive-plant,  209. 
Sepal,  148,  150,  174,  179. 
Sequoia.    See  "  Red-wood." 
Sessile  leaf,  170. 
Shepherdia,  206. 

Shepherd' s-purse,  173-180;  Figs.  93-95. 
gross  anatomy  of  stem,  173. 
leaf,  124,  173. 
root,  173. 
branches,  174. 
flower,  174,  175. 
fruit  and  seed,  175. 
histology  of  root,  175, 176. 
stem,  177. 
leaf,  177,  178. 

development  of  flower,  179. 
ovule,  179. 
embryo,  180. 

Shooting-star,  212 ;  Fig.  117. 
Sieve-tube,  111,  137. 
Silene.    See  "  Catch-fly." 
Silicon,  2. 
Simple  leaf,  170. 


INDEX. 


251 


Siphonese,  22,  34. 

Sisyrinchium.  See  "  Blue-eyed  grass." 

Skunk  cabbage,  157. 

Slime  mould,  12,  14;  Fig.  5. 

plasmodium,  12. 

movements,  13. 

feeding,  13. 

spore-cases,  13. 

spores,  13. 

germination  of  spores,  14. 
Smart-weed.    See  "  Polygonium." 
Smilacese,  155. 
Smoke-tree,  198. 
Smut,  64,  65. 

Smut-corn.    See  "  Ustillago." 
Snow-berry,  223. 
Soft-tissue,  112. 
Solanum,  -ese,  215. 
Solomon's  Seal,  154;  Fig.  83. 
Soredium,  74. 
Sorus,  118. 

SpadiciflorsB,  153,  157. 
Spadix,  157. 

Spanish  bayonet.    See  "  Yucca." 
Sparganium.    See  "Bur-reed." 
Speedwell.    See  "  Veronica." 
Spermaphyte,  128-129. 
Spermatozoid,  28,  36,  40,  46,  51,  89,  96, 

106,  122. 

Spermogonium,  79,  80. 
Sphagnum,  -acese,  99, 100. 

sporogonium,  100. 

leaf,  100. 
Spice-bush,  188. 

Spiderwort,  6,  151,  157 ;  Fig.  85. 
Spigelia.    See  "Pink-root." 
Spike,  181. 

Spikenard,  202 ;  Fig.  110. 
Spinach,  184. 

Spindle-tree,  199 ;  Fig.  109. 
Spirogyra,  30-32;  Fig.  18. 

structure  of  cells,  30. 

starch,  31. 

cell-division,  31. 

sexual  reproduction,  32. 


Sporangium,  55,  62,  113,  121,  122,  131, 
148,  151,  179. 

Spore-case.    See  "  Sporangium." 

Spore-fruit,  51,  66,  69,  70,  73,  83. 

Spore-sac.    See  "  Ascus." 

Sporocarp.    See  "Spore-fruit." 

Sporogonium,  87,  90,  102,  123. 

Sporophyll,  128,  131,  148. 

Sporophyte,  109. 

Spring-beauty,  185 ;  Fig.  98. 

Spruce,  142. 

Spurge.    See  "  Euphorbia." 

Squash,  221. 

Staining  agents,  4,  231,  233. 

Stamen,  128,  143,  148,  174,  179. 

Standard,  207. 

Staphylea.    See  "  Bladder-nut." 

Starch,  31,  95,  152. 

Statice.    See  '•  Sea-rosemary." 

Stellaria.    See  ' '  Chickweed . ' ' 

Stemonitis,  13 ;  Fig.  5. 

Sticta,  75 ;  Fig.  45. 

Stigeoclonium,  26;  Fig.  14. 

Stigma,  145,  148, 175,  179. 

St.  John's-wort,  195;  Fig.  105. 

Stock,  192. 

Stoma.    See  "  Breathing-pore." 

Stone-crop,  202 ;  Fig.  113. 

Stone-fruit,  206. 

Stone-wort.    See  "  Characese." 

Stony-tissue,  110. 

Stramonium,  215. 

Strawberry,  171,  202,  206;  Fig.  113. 

Style,  148,  175,  179. 

Stylophorum,  187;  Fig.  103. 

Sugar,  8,  145. 

Sulphur,  2. 

Sumach,  198 ;  Fig.  108. 

Sun-dew,  192,  193 ;  Fig.  104. 

Sun-flower,  224. 

Suspensor,  180. 

Sweet-flag,  157. 

Sweet-potato,  214. 

Sweet-scented  shrub.  See  "  Caly can- 
thus." 


252 


BOTANY. 


Sweet-william,  185. 
Sycamore,  183. 
Sympetalse,  210. 

Symphoricarpus.  See  "  Snow-berry." 
Symplocarpus.  See  "  Skunk-cabbage." 
Synergidae,  144. 

Syringa,    199;    Fig.    111.      See   also 
"  Lilac." 

Tamarack,  142. 

Tap-root,  131, 173. 

Taraxacum.    See  "  Dandelion." 

Taxodium.    See  "  Cypress." 

Taxus.    See  "Yew." 

Teasel,  224;  Fig.  124. 

Tecoma.    See  "  Trumpet-creeper." 

Teleuto-spore,  80,  81. 

Tendril,  171. 

TerebinthinsB,  198. 

Tetraspore,  51,  52. 

Thistle,  173,  223;  Fig.  125. 

Thorn,  172. 

Thyme,  215. 

Thymeleacess,  206. 

Thymelinete,  206. 

Tilia,  -acese.    See  "  Linden." 

Tillandsia,  156;  Fig.  84. 

Tissue,  8. 

Tissue  system,  115. 

Toadstool,  82. 

Tobacco,  215. 

Tolypella,  40. 

Tomato,  215. 

Touch-me-not.    See  "  Jewel-weed." 

Tracheary  tissue,  110,  121,  177. 

Tracheid,  110,  138. 

Tradescantia.    See  "  Spiderwort." 

Trailing  arbutus,  211. 

Tremella,  81 ;  Fig.  51. 

Trichia,  13,  14 ;  Fig.  5. 

Trichogyne,  51. 

Tricoccse,  199. 

Triglochin.    See  "Arrow-grass." 

Trillium,  146,  154,  155 ;  Fig.  83. 

Triphragmium,  81. 


Tropceolum.    See  "  Nasturtium." 

Trumpet-creeper. 

Tuber,  120,  153,  172. 

TubiflorsB,  213. 

Tulip,  146. 

Tulip-tree,  187 ;  Fig.  100. 

Turnip,  192. 

Twin-leaf,  187; 'Fig.  101. 

Typha,  -acese.    See  "  Cat-tail." 

UlmacesB.    See  "Elm." 
Ulva.    See  "  Sea-lettuce." 
Umbelliferse.    See  "  Umbel-wort." 
Umbel-wort,  202. 
Umbelliflorse,  202. 
Uredineae,  77. 
Uromyces,  81 ;  Fig.  47. 
UrticinsR,  183. 
Usnea,  75 ;  Fig.  45. 
Ustillaginese.    See  "  Smut." 
Ustillago,  65;  Fig.  38. 
Utricularia.    See  "Bladder-weed." 
Uvularia.    See  "  Bellwort." 

Vaccinium.    See  "  Cranberry." 

Vacuole,  8. 

Valerian,  224 ;  Fig.  124. 

Valeriana,  -ese.   See  "  Valerian." 

Vallisneria.    See  "Eel-grass." 

Vanilla,  166. 

Vaucheria,  34-37;  Figs.  21,  22. 

structure  of  plant,  35. 

racemosa,  35. 

non-sexual  reproduction,  36. 

sexual  organs,  36. 

fertilization,  36. 

resting  spores,  37. 
Venus's  fly-trap,  192. 
Verbascum.    See  "  Mullein." 
Verbena,  -acese,  218;  Fig.  121. 
Veronica,  217 ;  Fig.  120. 
Vervein.    See  "  Verbena." 
Vessel,  121, 135, 150, 175,  177. 
Viburnum,  223;  Fig.  124. 
Victoria  regia,  190. 


INDEX. 


25S 


Vinca.    See  ' '  Periwinkle.' ' 
Vine,  199. 

Violet,  192 ;  Fig.  104. 
Viola,  -acesB.    See  "  Violet." 
Virginia  creeper,  171, 199. 
Vitis.    See  "  Grape." 
Vitacess.    See  "  Vine." 
Volvox,  12,20;  Fig.  10. 
VolvocinesB,  12,  19. 

Wall-flower,  192. 

Walnut,  183. 

Wandering-Jew,  157. 

Water  fern,  117. 

Water-leaf,  214;  Fig.  118. 

Water-lily.       See     "  Nymphsea," 

"  Castaha." 

Water-milfoil,  206;  Fig.  113. 
Water  mould.    See  "  Saprolegnia." 
Water  net,  24 ;  Fig.  11. 
Water-plantain,  167. 
Water-shield,  190. 
Water-starwort,  200. 
Wax-plant,  220. 
Wheat,  78. 

Wheat  rust,  78,  81 ;  Fig.  47. 
Whitlavia,  214. 
Wild  ginger,  224 ;  Fig.  126. 


Wild  onion,  230. 

Wild  parsnip,  202. 

Willow,  181-183;  Fig.  96. 

Willow-herb,  206,  226 ;  Fig.  113. 

Wing  (of  papilionaceous  flower), 208. 

Wintergreeu,  211. 

Wolffia,  159. 

Wood.    See"Xylem." 

Wood-sorrel,  197;  Fig.  107. 

Xylem,  110,  124,  135, 150,  173, 176. 

Yam,  154. 

Yeast,  63,  64;  Fig.  37. 

cause  of  fermentation,  63. 

reproduction,  64. 

systematic  position,  64. 
Yew,  141. 
Yucca,  153. 

Zanthoxylum.    See  "  Prickly  ash." 
Zingiber,  -acese.    See  "  Ginger." 
Zoology,  2. 

Zoospore,  25,  37,  58,  62. 
Zygnema,  33 ;  Fig.  19. 
Zygomorphy,  Zygomorphic,  164,   215, 
226. 


NATURAL  SCIENCE. 


Elements  of  Physics. 


A  Text-book  for  High  Schools  and  Academies.  By  ALFRED  P.  GAGE, 
A.M.,  Instructor  in  Physics  in  the  English  High  School,  Boston.  12mo. 
424  pages.  Mailing  Price,  $1.25;  Introduction,  $1.12;  Allowance  for  old 
book,  35  cents. 


rTlHIS  treatise  is  based  upon  the  doctrine  of  the  conservation  of 
energy,  which  is  made  prominent  throughout  the  work.  But 
the  leading  feature  of  the  book  —  one  that  distinguishes  it  from 
all  others  —  is,  that  it  is  strictly  experiment-teaching  in  its  method  ; 
i.e.,  it  leads  the  pupil  to  "read  nature  in  the  language  of  experi- 
ment." So  far  as  practicable,  the  following  plan  is  adopted  :  The 
pupil  is  expected  to  accept  as  fact  only  that  which  he  has  seen  or 
learned  by  personal  investigation.  He  himself  performs  the  larger 
portion  of  the  experiments  with  simple  and  inexpensive  apparatus. 
such  as,  in  a  majority  of  cases,  is  in  his  power  to  construct  with  the 
aid  of  directions  given  in  the  book.  The  experiments  given  are 
rather  of  the  nature  of  questions  than  of  illustrations,  and  precede 
the  statements  of  principles  and  laws.  Definitions  and  laws  are  not 
given  until  the  pupil  has  acquired  a  knowledge  of  his  subject  suffi- 
cient to  enable  him  to  construct  them  for  himself.  The  aim  of  the 
book  is  to  lead  the  pupil  to  observe  and  to  think. 


C.  F.  Emerson,  Prof,  of  Physics, 
Dartmouth  College :  It  takes  up  the 
subject  on  the  right  plan,  and  pre- 
sents it  in  a  clear,  yet  scientific,  way. 

Win.  Noetling,  Prof,  of  Rhetoric, 
Theory  and  Practice  of  Teaching, 
State  Normal  School,  Bloomsburg, 
Pa. :  Every  page  of  the  book  shows 
that  the  author  is  a  real  teacher  and 
that  he  knows  how  to  make  pupils 
think.  I  know  of  no  other  work  on 


the  subject  of  which  this  treats  that 
I  can  so  unreservedly  recommend  to 
all  wide-awake  teachers  as  this. 

B.  F.  Wright,  Supt.  of  Public 
Schools,  St.  Paul,  Minn.:  I  like  it 
better  than  any  text-book  on  physics 
I  have  seen. 

0.  H.  Roberts,  Prin.  of  High 
School,  San  Jose,  Gal.:  Gage's  Phys- 
ics is  giving  great  satisfaction. 


NATURAL   SCIENCE.  93 

Introduction  to  Physical  Science. 

By  A.  P.  GAGE,  Instructor  in  Physics  in  the  English  High  School,  Bos- 
ton, Mass.,  and  Author  of  Elements  of  Physics,  etc.  12mo.  Cloth, 
viii  +  353  pages.  With  a  chart  of  colors  and  spectra.  Mailing  Price, 
$1.10  ;  for  introduction,  $1.00  ;  allowance  for  an  old  book  in  exchange, 
30  cents. 

rriHE  great  and  constantly  increasing  popularity  of  Gage's  Ele- 
ments of  Physics  has  created  a  demand  for  an  equally  good 
but  easier  book,  on  the  same  plan,  suitable  for  schools  that  can 
give  but  a  limited  time  to  the  study.  The  Introduction  to  Physical 
Science  has  been  prepared  to  supply  this  demand. 

Accuracy  is  the  prime  requisite  in  scientific  text-books.  A 
false  statement  is  not  less  false  because  it  is  plausible,  nor  an  in- 
conclusive experiment  more  satisfactory  because  it  is  diverting. 
In  books  of  entertainment,  such  things  may  be  permissible ;  but 
in  a  text-book,  the  first  essentials  are  correctness  and  accuracy. 
It  is  believed  that  the  Introduction  will  stand  the  closest  expert 
scrutiny.  Especial  care  has  been  taken  to  restrict  the  use  of  scien- 
tific terms,  such  as  force,  energy,  power,  etc.,  to  their  proper  signifi- 
cations. Terms  like  sound,  light,  color,  etc.,  which  have  commonly 
been  applied  to  both  the  effect  and  the  agent  producing  the  effect 
have  been  rescued  from  this  ambiguity. 

Recent  Advances  in  physics  have  been  faithfully  recorded, 
and  the  relative  practical  importance  of  the  various  topics  has  been 
taken  into  account.  Among  the  new  features  are  a  full  treatment 
of  electric  lighting,  and  descriptions  of  storage  batteries,  methods 
of  transmitting  electric  energy,  simple  and  easy  methods  of  making 
electrical  measurements  with  inexpensive  apparatus,  the  compound 
steam-engine,  etc.  Static  electricity,  which  is  now  generally  re- 
garded as  of  comparatively  little  importance,  is  treated  briefly; 
while  dynamic  electricity,  the  most  potent  and  promising  physical 
element  of  our  modern  civilization,  is  placed  in  the  clearest  light 
of  our  present  knowledge. 

In  Interest  and  Availability  the  Introduction  will,  it  is 
believed,  be  found  no  less  satisfactory.  The  wide  use  of  the 
Elements  under  the  most  varied  conditions,  and,  in  particular, 
the  author's  own  experience  in  teaching  it,  have  shown  how  to 
improve  where  improvement  was  possible.  The  style  will  be  found 


94 


NATURAL   SCIENCE. 


suited  to  the  grades  that  will  use  the  book.  The  experiments  are 
varied,  interesting,  clear,  and  of  practical  significance,  as  well  as 
simple  in  manipulation  and  ample  in  number.  Certain  subjects 
that  are  justly  considered  difficult  and  obscure  have  been  omitted ; 
as,  for  instance,  certain  laws  relating  to  the  pressure  of  gases  and 
the  polarization  of  light.  The  Introduction  is  even  more  fully 
illustrated  than  the  Elements. 

In  General.  The  Introduction,  like  the  Elements,  has  this  distinct 
and  distinctive  aim,  —  to  elucidate  science,  instead  of  "populariz- 
ing "  it ;  to  make  it  liked  for  its  own  sake,  rather  than  for  its  gilding 
and  coating  ;  and,  while  teaching  the  facts,  to  impart  the  spirit  of 
science,  —  that  is  to  say,  the  spirit  of  our  civilization  and  progress. 


George  E.  (Jay,  Prin.  of  High 
School,  Maiden,  Mass.:  With  the 
matter,  both  the  topics  and  their  pre- 
sentation, I  am  better  pleased  than 
with  any  other  Physics  I  have  seen. 

E.  H.  Perkins,  Supt.  of  Schools, 
Chicopee,  Mass. :  I  have  no  doubt 
we  can  adopt  it  as  early  as  next 
month,  and  use  the  same  to  great  ad- 
vantage in  our  schools.  (Feb.  6, 1888.) 

Mary  E.  Hill,  Teacher  of  Physics, 
Northfield  Seminary,  Mass. :  I  like 
the  truly  scientific  method  and  the 
clearness  with  which  the  subject  is 
presented.  It  seems  to  me  admirably 
adapted  to  the  grade  of  work  for 
which  it  is  designed.  (Mar.  5,  '88.) 

JohnPickard,  Prin.  of  Portsmouth 
High  School,  N.H. :  I  like  it  exceed- 
ingly. It  is  clear,  straightforward, 
practical,  and  not  too  heavy. 

Ezra  Brainerd,  Pres.  and  Prof, 
of  Physics,  Middlebury  College,  Vt. : 
I  have  looked  it  over  carefully,  and 
regard  it  as  a  much  better  book  for 
high  schools  than  the  former  work. 
(Feb.  6,  1888.) 

James  A.  De  Boer,  Prin.  of  High 
School,  Montpelier,  Vt. :  I  have  not 
only  examined,  but  studied  it,  and 
consider  it  superior  as  a  text-book  to 
any  other  I  have  seen.  (Feb.  10,  '88.) 


E.  B.  Eosa,  Teacher  of  Physics, 
English  and  Classical  School,  Provi- 
dence, JKJ. :  I  think  it  the  best  thing 
in  that  grade  published,  and  intend 
to  use  it  another  year.  (Feb.  23,  '88.) 

G.  H.  Patterson,  Prin.  and  Prof,  of 
Physics,  Berkeley  Sch.,  Providence, 
K.I.:  A  very  practical  book  by  a 
practical  teacher.  (Feb.  2,  1888.) 

George  E.  Beers,  Prin.  of  Evening 
High  School,  Bridgeport,  Conn.  : 
The  more  I  see  of  Professor  Gage's 
books,  the  better  I  like  them.  They 
are  popular,  and  at  the  same  time 
scientific,  plain  and  simple,  full  and 
complete.  (Feb.  18,  1888.) 

Arthur  B.  Chaff ee,  Prof,  in  Frank- 
lin College,  Ind. :  I  am  very  much 
pleased  with  the  new  book.  It  will 
suit  the  average  class  better  than  the 
old  edition. 

W.  D.  Kerlin,  Supt.  of  Public 
Schools,  New  Castle,  Ind.:  I  find 
that  it  is  the  best  adapted  to  the 
work  which  we  wish  to  do  in  our 
high  school  of  any  book  brought  to 
my  notice. 

C.  A.  Bryant,  Supt.  of  Schools, 
Paris,  Tex. :  It  is  just  the  book  for 
high  schook.  I  shall  use  it  next 
year. 


NATURAL   SCIENCE.  95 

Introduction  to  Chemical  Science. 


By  R.  P.  WILLIAMS,  Instructor  in  Chemistry  in  the  English  High 
School,  Boston.  12mo.  Cloth.  216  pages.  Mailing  Price,  90  cents;  for 
introduction,  80  cents;  Allowance  for  old  book  in  exchange,  25  cents. 

TN    a  word,  this  is  a  working  chemistry  —  brief  but  adequate. 
Attention  is  invited  to  a  few  special  features  :  — 

1.  This  book  is  characterized  by  directness  of  treatment,  by  the 
selection,  so  far  as  possible,  of  the  most  interesting  and  practical 
matter,  and  by  the  omission  of  what  is  unessential. 

2.  Great  care  has  been   exercised  to  combine  clearness  with 
accuracy  of  statement,  both  of  theories  and  of  facts,  and  to  make 
the  explanations  both  lucid  and  concise. 

3.  The  three  great  classes    of    chemical    compounds  —  acids, 
bases,  and  salts  —  are  given  more  than  usual  prominence,  and  the 
arrangement  and  treatment  of  the  subject-matter  relating  to  them 
is  believed  to  be  a  feature  of  special  merit. 

4.  The  most  important  experiments  and  those  best  illustrating 
the  subjects  to  which  they  relate,  have  been  selected  ;  but  the  modes 
of  experimentation  are  so  simple  that  most  of  them  can  be  per- 
formed by  the  average  pupil  without  assistance  from  the  teacher. 

5.  The  necessary  apparatus  and  chemicals  are  less  expensive 
than  those  required  for  any  other  text-book  equally  comprehensive. 

6.  The  special  inductive  feature  of  the  work  consists  in  call- 
ing attention,  by  query  and  suggestion,  to  the  most  important 
phenomena  and  inferences.     This  plan  is  consistently  adhered  to. 

7.  Though  the  method  is  an  advanced  one,  it  has  been  so  sim- 
plified that  pupils  experience  no  difficulty,  but  rather  an  added 
interest,   in  following  it ;    the   author  himself    has    successfully 
employed  it  in  classes  so  large  that  the  simplest  and  most  practical 
plan  has  been  a  necessity. 

8.  The  book  is  thought  to  be  comprehensive  enough  for  high 
schools  and  academies,  and  for  a  preparatory  course  in  colleges  and 

/professional  schools. 

9.  Those  teachers  in  particular  who  have  little  time  to  prepare 
experiments  for  pupils,  or  whose  experience  in  the  laboratory  has 
been  limited,  will  find  the  simplicity  of  treatment  and  of  experi- 
mentation well  worth  their  careful  consideration. 

Those  who  try  the  book  find  its  merits  have  not  been  overstated. 


96 


NATURAL   SCIENCE. 


A.  B.  Aubert,  Prof,  of  Chemistry, 
Maine  State  College,  Orono,  Me.  : 
All  the  salient  points  are  well  ex- 
plained, the  theories  are  treated  of 
with  great  simplicity ;  it  seems  as  if 
every  student  might  thoroughly  un- 
derstand the  science  of  chemistry 
when  taught  from  such  a  work. 

H.  T.  Fuller,  Pres.  of  Polytechnic 
Institute,  Worcester,  Mass. :  It  is 
clear,  concise,  and  suggests  the  most 
important  and  most  significant  ex- 
periments for  illustration  of  general 
principles. 

Alfred  S.  Koe,  Prin.  of  High 
School,  Worcester,  Mass. :  I  am  very 
much  pleased  with  it.  I  think  it  the 
most  practical  book  for  actual  work 
that  I  have  seen. 

Frank  M.  Gilley,  Science  Teacher, 
High  School,  Chelsea,  Mass. :  I  have 
examined  the  proof-sheets  in  connec- 
tion with  my  class  work,  and  after 
comparison  with  a  large  number  of 
text-books,  feel  convinced  that  it  is 
superior  to  any  yet  published. 


G.  S.  Fellows,  Teacher  of  Chemis- 
try, High  School,  Washington,  D.C.: 
The  author's  method  seems  to  us  the 
ideal  one.  Not  only  are  the  theo- 
retical parts  rendered  clear  by  ex- 
periments performed  by  the  student 
himself,  but  there  is  a  happy  blend- 
ing of  theoretical  and  applied  chem- 
istry as  commendable  as  it  is  unusual. 

J.  I.  D.  Hines,  Prof,  of  Chemistry, 
Cumberland  University,  Lebanon, 
Tenn. :  I  am  very  much  pleased  with 
it,  and  think  it  will  give  the  student 
an  admirable  introduction  to  the  sci- 
ence of  chemistry. 

Horace  Phillips,  Prin.  of  High 
School,  Elkhart,  Ind. :  My  class  has 
now  used  it  three  months.  It  proves 
the  most  satisfactory  text-book  in 
this  branch  that  I  have  ever  used. 
The  cost  of  apparatus  and  material 
is  very  small. 

0.  S.  Wescott,  Prin.  North  Divis- 
ion H.  Sch.,  Chicago :  My  chemistry 
professor  says  it  is  the  most  satisfac- 
tory thing  he  has  seen,  and  hopes  we 
may  be  able  to  have  it  in  future. 


Laboratory  Manual  of  General  Chemistry. 

By  K.  P.  WILLIAMS,  Instructor  in  Chemistry,  English  High  School,  Bos- 
ton, and  author  of  Introduction  to  Chemical  Science.  12mo.  Boards. 
xvi  +  200  pages.  Mailing  Price,  30  cents  ;  for  Introduction,  25  cents. 


Manual,  prepared  especially  to  accompany  the  author's 
Introduction  to  Chemical  Science,  but  suitable  for  use  with 
any  text-book  of  chemistry,  gives  directions  for  performing  one 
hundred  of  the  more  important  experiments  in  general  chemistry 
and  metal  analysis,  with  blanks  and  a  model  for  the  same,  lists 
of  apparatus  and  chemicals,  etc. 

The  Manual  is  commended  as  well-designed,  simple,  convenient, 
and  cheap,  —  a  practical  book  that  classes  in  chemistry  need. 


W.  M.  Stine,  Prof,  of  Chemistry, 
Ohio  University,  Athens,  0.:  It  is  a 
work  that  has  my  heartiest  endorse- 
ment. I  consider  it  thoroughly  peda- 


gogical in  its  principles,  and  its  r/se 
must  certainly  give  the  student  the 
greatest  benefit  from  his  chemical 
drill.  (Dec.  30, 1888.) 


NATURAL   SCIENCE.  97 

Young's  General  Astronomy. 

A  Text-book  for  colleges  and  technical  schools.  By  CHARLES  A.  YOUNG, 
Ph.D.,  LL.D.,  Professor  of  Astronomy  in  the  College  of  New  Jersey,  and 
author  of  The  Sunt  etc.  8vo.  viii  +  551  pages.  Half-morocco.  Illustrated 
with  over  250  cuts  and  diagrams,  and  supplemented  with  the  necessary 
tables.  Introduction  Price,  $2.25.  Allowance  for  an  old  book  in  ex- 
change, 40  cents. 

rpHE  object  of  the  author  has  been  twofold.  First  and  chiefly, 
to  make  a  book  adapted  for  use  in  the  college  class-room ;  and, 
secondly,  to  make  one  valuable  as  a  permanent  storehouse  and 
directory  of  information  for  the  student's  use  after  he  has  finished 
his  prescribed  course. 

The  method  of  treatment  corresponds  with  the  object  of  the 
book.  Truth,  accuracy,  and  order  have  been  aimed  at  first,  with 
clearness  and  freedom  from  ambiguity. 

In  amount,  the  work  has  been  adjusted  as  closely  as  possible  to 
the  prevailing  courses  of  study  in  our  colleges.  The  fine  print 
may  be  omitted  from  the  regular  lessons  and  used  as  collateral 
reading.  It  is  important  to  anything  like  a  complete  view  of 
the  subject,  but  not  essential  to  a  course.  Some  entire  chapters 
can  be  omitted,  if  necessary. 

New  topics,  as  indicated  above,  have  received  a  full  share  of 
attention,  and  while  the  book  makes  no  claims  to  novelty,  the 
name  of  the  author  is  a  guarantee  of  much  originality  both  of 
matter  and  manner. 

The  book  will  be  found  especially  well  adapted  for  high  school 
and  academy  teachers  who  desire  a  work  for  reference  in  supple- 
menting their  brief  courses.  The  illustrations  are  mostly  new,  and 
prepared  expressly  for  this  work.  The  tables  in  the  appendix  are 
from  the  latest  and  most  trustworthy  sources.  A  very  full  and 
carefully  prepared  index  will  be  found  at  the  end. 

The  eminence  of  Professor  Young  as  an  original  investigator 
in  astronomy,  a  lecturer  and  writer  on  the  subject,  and  an 
instructor  of  college  classes,  and  his  scrupulous  care  in  pre- 
paring this  volume,  led  the  publishers  to  present  the  work  with 
the  highest  confidence ;  and  this  confidence  has  been  fully  justified 
by  the  event.  More  than  one  hundred  colleges  adopted  the  work 
within  a  year  from  its  publication. 


NATURAL   SCIENCE.  99 

Young's  Elements  of  Astronomy. 

A  Text-Book  for  use  in  High  Schools  and  Academies.  With  a  Uranog- 
raphy.  By  CHARLES  A.  YOUNG,  Ph.D.,  LL.D.,  Professor  of  Astronomy 
in  the  College  of  New  Jersey  (Princeton),  and  author  of  A  General 
Astronomy,  The  Sitn,  etc.  12mo.  Half  leather,  x  +  472  pages,  and 
four  star  maps.  Mailing  Price,  $1.55;  for  Introduction,  $1.40;  allow- 
ance for  old  book  in  exchange,  30  cents. 

Uranography. 

From  Young's  Elements  of  Astronomy.  12mo.  Flexible  covers.  42 
pages,  besides  four  star  maps.  By  mail,  35  cents;  for  Introduction, 
30  cents. 

HHHIS  volume  is  a  new  work,  and  not  a  mere  abridgment  of  the 
author's  General  Astronomy.  Much  of  the  material  of  the  larger 
book  has  naturally  been  incorporated  in  this,  and  many  of  its  il- 
lustrations are  used ;  but  everything  has  been  worked  over,  with 
reference  to  the  high  school  course. 

Special  attention  has  been  paid  to  making  all  statements  correct 
and  accurate  as  far  as  they  go.  Many  of  them  are  necessarily  incom- 
plete, on  account  of  the  elementary  character  of  the  work;  but  it 
is  hoped  that  this  incompleteness  has  never  been  allowed  to  become 
untruth,  and  that  the  pupil  will  not  afterwards  have  to  unlearn 
anything  the  book  has  taught  him. 

In  the  text  no  mathematics  higher  than  elementary  algebra  and 
geometry  is  introduced  ;  in  the  foot-notes  and  in  the  Appendix  an 
occasional  trigonometric  formula  appears,  for  the  benefit  of  the 
very  considerable  number  of  high  school  students  who  understand 
such  expressions.  This  fact  should  be  particularly  noted,  for  it  is 
a  special  aim  of  the  book  to  teach  astronomy  scientifically  without 
requiring  more  knowledge  and  skill  in  mathematics  than  can  be 
expected  of  high  school  pupils. 

Many  things  of  real,  but  secondary,  importance  have  been  treated 
of  in  fine  print ;  and  others  which,  while  they  certainly  ought  to  be 
found  within  the  covers  of  a  high  school  text-book  of  astronomy, 
are  not  essential  to  the  course,  are  relegated  to  the  Appendix. 

A  brief  Uranography  is  also  presented,  covering  the  constella- 
tions visible  in  the  United  States,  with  maps  on  a  scale  sufficient 
for  the  easy  identification  of  all  the  principal  stars.  It  includes 
also  a  list  of  such  telescopic  objects  in  each  constellation  as  are 
easily  found  and  lie  within  the  power  of  a  small  telescope. 


NATURAL    SCIENCE.  101 

Plant  Organization. 

By  R.  HALSTED  WARD,  M.D.,  F.R.M.S.,  Professor  of  Botany  in  the  Rens 
selaer  Polytechnic  Institute,  Troy,  N.Y.  Quarto.  176  pages.  Illustrated. 
Flexible  boards.  Mailing  Price,  85  cents  ;  for  Introd.,  75  cents. 

TT  consists  of  a  synoptical  review  of  the  general  structure  and 
morphology  of  plants,  clearly  drawn  out  according  to  biological 
principles,  fully  illustrated,  and  accompanied  by  a  set  of  blanks 
for  written  exercises  by  pupils.  The  plan  is  designed  to  encourage 
close  observation,  exact  knowledge,  and  precise  statement. 

A  Primer  of  Botany. 

By  Mrs.  A.  A.  KNIGHT,  of  Robinson  Seminary,  Exeter,  N.H.     12mo. 
Boards.    Illus.   vii  +  115  pp.    Mailing  Price,  35  cents  ;  for  Introd.,  30  cents. 


Primer  is  designed  to  bring  physiological  botany  to  the 
level  of  primary  and  intermediate  grades. 

Outlines  of  Lessons  in  Botany. 

For  the  use  of  teachers,  or  mothers  studying  with  their  children.  By 
Miss  JANE  H.  NEWELL.  Part  I.:  From  Seed  to  Leaf.  Sq.  16mo.  Illus. 
150  pp.  Cloth.  Mailing  Price,  55  cents  ;  for  Introd.,  50  cents. 

book  aims  to  give  an  outline  of  work  for  the  pupils  them- 
selves.     It  follows  the  plan  of  Gray's  First  Lessons  and  How 
Plants  Grow,  and  is  intended  to  be  used  wif  h  either  of  these  books. 

A  Reader  in  Botany. 

Selected  and  adapted  from  well-known  Authors.  By  Miss  JANE  H. 
NEWELL.  Part  I.  :  From  Seed  to  Leaf.  12mo.  Cloth,  vi  +  209  pp. 
Mailing  Price,  70  cents;  for  Introd.,  60  cents. 

rpHIS  book  follows  the  plan  of  the  editor's  Outlines  of  Lessons  in 
Botany  and  Gray's  Lessons,  and  treats  of  Seed-Food,  Movements 
of  Seedlings,  Trees  in  Winter,  Climbing  Plants,  Insectivorous  Plants, 
Protection  of  Leaves  from  the  Attacks  of  Animals,  etc. 

Little  Flower-People. 

By  GERTRUDE  ELISABETH  HALE.  Sq.  12mo.  Illus.  Cloth,  xiii  +  85 
pp.  Mailing  Price,  50  cents  ;  for  Introd.,  40  cents. 

FT1HE  aim  of  this  book  is  to  tell  some  of  the  most  important  ele- 
mentary facts  of  plant-life  in  such  a  way  as  to  appeal  to  the 
child's   imagination    and  curiosity,  and  to  awaken  an  observant 
interest  in  the  facts  themselves. 


#rf6 


YB  36056 


MI87509 


THE  UNIVERSITY  OF  CALIFORNIA  LIBRARY 


